Knife Thrower is too weak, it should not have the disadvantage of taking 1000 damage.
... wut? It does 1000 extra damage and then dies you are basically saying to remove the part where the unit dies
so if it can survive after having a 100% destroying without dying it can do it again so if he doesn't die (meaning he has high health) it will be so good that some armies on the player armies will have an high hp knife thrower basically almost removing the casual players