I anvil'd together a Prot 4 DiamondArmor and a Proj4 EnchantedBook and in the combined slot it was what it was supposed to be, but once I put it into my invent proj4 was no longer there and the book and exp where also gone. I logged thinking I may just not be able to see it cause it happens sometimes but still nothing... T_T
Yes, you combine enchantments like that Prot or any damage type for weapons the general purpose one will stay and the other will just poof so protection would stay protection and the other enchant will just vanish, while sword Sharpness will stay and other damage types will just poof as well. Keep in mind that the anvil should just show you that it will combine but only one of the enchants is on it.
