Rather than put these notes in a PM and have them lost forever, I thought I'd reply them into your post so that someone else randomly searching the net might find a couple bits semi useful. You asked some good questions so I got out my old books and had a read.
The short summary for your purposes is that if you want to paint the QueztalTeculotl all green because it says quetzal, go for it if it makes you happiest. In a wargaming context, nobody but extremely well read gamers are going to have a clue what it's about anyway. It was definitely used once, for part of one day, by a person who was given it to wear, acting as a hero in a skirmish situation accompanied only by 4 other warriors, who then is never mentioned again. The assumption is that he is dead because his name is not further recounted in the lists of brave warriors, and Cuauhtemoc also said that he would die in it. The Nahua text says he neither died, nor was he captured, and implies that he just vanished. Following this incident there are several days of non combat, then Cuauhtemoc flees and is captured. This warrior's skirmishing is the last combat of the war in Sahagun's text.
Did the original owner Ahuitzotl ever wear it himself when he was alive, outside of ceremony? We'll never know.
This suit is truly obscure, and only applicable obviously for a hero figure, and not in a formation of warriors you'd encounter any old time. You questioned whether it is a full suit version, or skirted version. Two things, every illustration of a bird outfitted figure in the Tenoch illustrations I have seen have all been full body suits, secondly, these illustrations always reproduce the original colour of that particular bird. Artistic stylisation or artistic accuracy? Maybe either way. Surely if jaguars can be reproduced in green feathers, then why not perhaps an eagle or teculotl if your imagination wants to lean that way. The only owl suit I recall illustrated is also by Sahagun in the Primeros, in the illustration for the Atamalcualiztli ceremony. Obviously that is a full body suit with natural colours.
I'm looking for information on the suit of Auitzol dressed on quetzal owl suit?
This is quetzaltecolot and owl aztec:
Anyway, onto nerdy notes and bits of thought. Sorry these are a bit mixed up, I added to them over a week or so and haven't gone back to straighten them up into a more coherent narrative:
There are 4 mentions of the QuetzalTeculotl in book 12 of the Florentine, all in chapter 38, in 3 consecutive paragraphs. I had to go back and dig out my codices to look specifically at the original Nahua and Spanish text. The name is written the same in both the Spanish and Nahua texts, and the Spanish commentary doesn't give any extra clues to what is going on. Chapter 38 doesn't have any illustrations either
Interestingly the same paragraph that first mentions QuetzalTeculotl also has near its end the word tlacateculotl, yet Dibble & Anderson do not translate this as owl person but simply as devil/demon, which is what it is called also in Spanish. So what I'm saying is QueztalTeculotl is the word in both Spanish and Nahua texts, but the word TlacaTeculotl is written in Nahua, but in Spanish is written as demonio. Curious. The only clue you get to anything specific about the suit is in the Nahua it says that the quetzalli feathers go spreading. Quetzalli are specifically the long tail feathers of the quetzal bird, and are the long plumes used in shield borders, warrior sapote skirt lower hems, the long tail feather bundles on war suit helms or the long feathers on the back of a quetzal pamitl.
I don't recall the suit mentioned anywhere else, or even this particular incident mentioned in any other conquest accounts.
As you noted, Sahagun mentions this suit was one of the war suits of the former king Ahuitzol. He had at least 2 other suits from memory.
The interesting part of the story is the fact that this suit was even used in this conquest episode, for two reasons.
Firstly, by this stage of the conflict, the remaining Tenochs had fled to Tlatelolco. So clearly they had taken this suit of Ahuitzotl's from storage and carried it with them (ancestor veneration, one of the histories talks about keeping these things.) It would seem perfectly natural for Cauahtemoc to take his dad's suit as a personal treasure. This also indicates that they had also taken at least some of the other treasures of Ahuitzotl (if not also that of other former kings and the empire in general.)
Secondly, by this stage of the war, the numbers of skilled warriors must have been quite low as the military defences crumbled and some fled, many were killed, and the allied warriors from other towns defected to the apparent winning side. Seeking a way to inspire the remaining Tenoch/Tlatelolcan warriors, and to scare the opponents, they hit upon the idea of putting the suit of Ahuitzotl on a deserving warrior. They settled upon a warrior named (or titled) Tlapaltecatl Opochtzin (perhaps translated as the hunting lord from/of the house of many colours, and it should be noted one of the first founding lords of Tlatelolco was named Opochtli so perhaps he is a direct descendant of this lineage). He came from the barrio (or calpulli) called Coatlan, which the Spanish text clarifies as the barrio in Tlatelolco near the laperrocha (some type of rock/hill thing, my poor skills put it as a flat topped rocky hill rather than a dog??) called Santa Catalina in post conquest times. Therefore, this warrior is from a different but closely related tribe to the Tenochs, the Tlatelolcans. So to really break down all kinds of taboos, they put the sacred, personalised suit of a dead king onto a warrior from a different tribe who was also of a lower social class.
Stepping back to look at the Nahua part words, they are quetzal and teculot.
Your original contention is that quetzal means composed all of quetzal feathers, but I have not seen any translation of the adjective quetzal come to this conclusion. Various translations put quetzal at rich/precious, princely/royal, or iridescent depending on the context. Generally it is simply translated as precious.
A couple examples of the word in use for context, paraphrased from Florentine book 11:
QuetzalTotol which is the quetzal trogon, or more commonly the resplendent trogon. The feathers are described as iridescent, which D&A translate as glistening. These are the feathers we talk of/imagine when queztal is mentioned. The tail feathers are specifically referred to as quetzalli and often talk of featherwork refers specifically to quetzalli feathers. This includes the sapote skirts in warsuits and the feather fringes to shields. I've always imagined them as a nice mid green, the translations call it chilli green, but while staring at pictures of resplendent quetzals I noticed paintings always show them green but photos show them as a more turquoise blue/green. It appears as though this blue/green shift is the iridescence, and observing the banner given to Cortez that is now in Vienna, the colours of the queztalli feathers used are for sure iridescent and shift between beautiful greens and blues. Probably way more technical than someone painting toy soldiers needs to get to.
Quetzalatzcalli which roughly translates as quetzal shell - the shell which is rough and rotted bone like on the outside, but on the inside shimmers with colours of red and blue and green and yellow etc (i.e. iridescent/pearly like a like a rainbow) I believe it's a species of oyster
QuetzalHuitzilin which roughly translates as quetzal hummingbird, which is the broad tailed hummingbird, and is described with an iridescent green back feathers with the rest of the bird in other colours
QuetzalTezolocton which is the green winged teal/duck, described as such in Nahua because the head is ornamented with feathers that are like a quetzal feather. [i.e. they are also iridescent green]Most of the duck though is in other earthier colours.
There are several plants that are also a quetzalxxx, but try as I might I can't imagine any of these plant species having iridescence that would justify the quetzal adjective. Perhaps I'd need to see them in person and I'd get it.
Clearly none of these things are all green, and the quetzal component refers to a specific part or appearance of that item.
Rolling over to the things we're really excited about, war equipment.
Several items are described with a quetzal adjective.
QuetzalPatzactli - usually described not as a banner made of quetzal feathers, but a banner made of varied rich and precious feathers. Clearly including quetzalli as the outside fringe of feathers, but many other feathers also in bands
ichimal QuetzalXicalculiuhqui - usually translated as the quetzal shield with the stepped fret (or marketplace) design. It has no long quetzalli kind of feathers attached to it in the Primeros commentary/illustration, and obviously in this case is half red and half green. The quetzal may refer to the green half, or may refer to it being precious/lordly, which in this context it also is.
QuetzalPapalotl - the quetzal butterfly back banner, or the precious butterfly back banner. The core of it is green, with the fringes and extremities all in yellow. It reminds me of the Malachite butterfly (Siproeta stelenes) It has no special quetzalli feathers on it except the long plumes at the top common to just about all banners, so the quetzal component may refer to the green bit of the butterfly body? Perhaps they are the quetzal tzinitzcan feathers. Or alternately, this is a tlatoani suit, the banner is the princely butterfly if the quetzal word is translated that way rather than as green
QuetzalCuexyo quetzal huaxtec shield. Illustrated in the Primeros, it is however drawn in red rather than green. It is hard to determine why this shield would have quetzal attached to it as a description, except perhaps one band of feathers in the middle as green, which may mean that short band is of quetzal feathers, or it's just a translation/typo error in the original nahua writing vs illustration
QuetzalPamitl - quetzal flag banner. The banner is made of quetzalli feathers as the outer line of feathers, and yellow feathers as the base line of feathers
QuetzalQuaquavitl quetzal horn helm. This is mostly of yellow feathers, and has no quetzal feathers aside from a small cup on each side with a spray of quetzalli feathers coming from each cup.
QuetzalTzitzimitl - quetzal demon of the air. typical tzitzimitl with a sprinkling of quetzalli feathers through the hair line.
and so on and so on through items described as quetzal something. Most have a part of quetzal feathers, from a very small amount, to possibly none, to possibly a large portion of it. Even the QuetzalTotol back banner ( the back banner that is literally the quetzal bird, has the natural colours of the quetzal bird with red, blue and greens on it. There are other items in green such as the xolopapalotl which simply translates as the dark yellow butterfly back banner, but which looks extremely similar to the quetzalpapalotl and is drawn in green.
The point is that saying quetzal something does not make something all green, in fact nothing described as quetzal something is all green.
The second part of the name is teculotl. It's usually just translated as owl, but that's not correct enough. The Nahua makes it clearer that it refers specifically to the great horned owl (Buho Cornado), so the shape and markings of this suit should form a reasonable representation of this specific bird. This part of the name is pretty simple. The way the horns are, I would very much lean to those horns being quetzalli most likely the way they are depicted on the quetzalquaquavitli helm. Wings or no wings, claws or no claws? Based on the way eagles are also variously drawn, pick what you like, though I'd guess yes definitely if it's a ceremonial based suit, for a combat based one, maybe not. The stylisation of the suit is still going to come down to a personal opinion of how you feel they did things based on the contradictory and incomplete evidence of other similar bird suits. In some cases anything could be possible, there are ceremonial instances of jaguar suits with bird wings
though I think that does get backed up by textual evidence also that says a specific warrior wore a combat suit composed of both jaguar and eagle parts.