I've noticed that some battle items have status ''Semi-breakable''. I know that such items as potions for example are Breakable and can be used only 1 time.
So, what means ''Semi-breakable'' (f.e., Cuirass of the Literati or Killdeer)? How many times I can use such item in a battle?

Semi-breakable means that the item may break for the duration of the battle, but there's no chance of losing the item - you just lose the use of it for the rest of that battle.
Some of them are one use per battle, some of them have a percetage chance of breaking.