Don't know if this is intended or a bug, but when using manasteel armor (haven't tested the other armor sets yet) with thorns on it and receiving damage, the thorns durability damage does not go to the mana tablet in the inventory but it damages the armor itself instead.

Using botania version r1.1-75 and forge 10.12.2.1147 (Minecraft 1.7.2)

There isn't anything I can do about this. Thorns skips the forge damage hooks. I requested a hook in forge to allow items to specify which enchantments can go on them but it wasn't accepted yet. Flagging as wontfix.

Ok that's a shame, thanks for replying so soon though ;D