So, I have noticed that when trying to combine enchantments with Equipment/Books, occasionally, the enchantments will not be applied, simply because there are too many enchantments on an item.
For example, I might have 2 books. One with, say, Unbreaking, Silk Touch, and Mending, and another with Protection, Aqua Affinity, and Frost Walker. In this example, (I'm not sure if these sets of enchantments will combine - will test this later) they will drop off an enchantment due to the "cap" of enchantments on an item.
I know that some Enchantments make others redundant (I.e. Silk Touch and Fortune, or vice-versa), so they will not combine. Others simply overlap - like the same enchantment of different levels (Unbreaking 3 overwrites Unbreaking 2). And obviously, enchantments that cannot be applied to equipment will simply not be, like Aqua Affinity on a pair of boots. However, after several tests, I haven't been able to figure out how the enchantments are dropped when combining them, outside of these parameters.
Is there any way I can determine which enchantment I will lose when combining books? And will this affect Curses too (Curse of the Vanishing/Curse of Binding)?