Looks like Citadel Six have a 15mm crusades range of decals in progress, but they are shields. The problem you'll have there is reversing the heraldry on the other side of the caparison. These days, I make my own decals, although I sometimes use them more as a guide to eventually paint over as I'm rubbish at drawing. Making your own isn't that difficult, they're not as good as commercially available ones, but perfectly passable particularly at a small scale. I made all my own decals for my 15mm samurai:
