Weapon becomes evil on backpack full of dynamite?

[Direporcupine]

Greetings Gentle folks.

Would someone be so kind as to explain to me what the effect of weapon becomes evil is on the backpack full of dynamite from Munchkin Cthulhu?

Cheers!

[MunchkinMan]

Because it has a variable bonus, you can't hit it with that Curse. It doesn't give you a bonus until after you've entered combat and decided how big to make the bonus.