The Great Helm is clipping through my skin's hair layer.
Image for reference:

Also, I've noticed some people mention that the textures for the helmet don't match the game, which is just because it is 32x resolution. I've seen some mods include optional resource packs with them, maybe this one could have one for a 16x version.
I converted the texture to 16x myself, which I've uploaded here, I give full permission to use it in the mod if you want to.
Crusade - Great Helm 16x.zip

EDIT: Lances not facing forwards on horseback was due to the NotEnoughAnimations mod.