Should probably make it so it can't go below 1. Because if you don't somehow miraculously realize that's how it works on your first ever use. Then the skill becomes useless for the rest of the run, which is what happened to me as well. I used it after a trap revealed multiple enemies, which did kill one of them, but didn't kill the rest. Which triggered the halving like 3 times and set damage to 0 instantly, killing the run, since late game you need your skill to do stuff, as enemy hp outscales weapon damage/charges.
Knight experience was solid though, won on my first run and everything worked as expected.