I've started re-reading the graphic novels. The armour is not strictly accurate in that he takes bits from a variety of RW time periods. So there are codpieces but also Morian helmets and late Medieval basinets. There are no pot helms that I can recall. There is an attempt to give the factions a distinctive look. No gun powder and magic seems generally low-key. Artesia is a witch and uses magic in battle, and she has a magic sword. She uses magic to amplify her voice when she gives the pre-battle speech (somewhat like in Harry Potter, but without a wand.) And she calls forth spirits from the sword to spread terror in the ranks of the foe. AFAIK, the other side didn't have any magic, beyond perhaps some magic weapons.
In one of the later books they battle a host which has undead warriors and IIRC she calls all captains with "magic" weapons to the fore (can't remember the term she uses.)
So magic is low-key, but there a lot of religious stuff - pre-battle omens and prayers, calling on the various goddesses for aid, plus post-battle rituals. There is a role-playing game but I have only skimmed the magic system so far. It seems that mages are "powered" by spirits which they can harness from old barrows and battle sites. So those locations are rated by how many viable spirits may be available. Magic seems to be [potentially] dangerous for the wielder, as well. A lot of the magic is related to spirits of various sort, some very like valkyrie who arrive to carry off the dead. Only Artesia can see them but the others all believe that these creatures are there.
The series is very nicely illustrated and well written. I highly recommend them, but with a warning that they are for mature readers and feature violence, nudity and sexual situations.
Howard