First, love you're additions to the game and the fact that its in the same style as the main book is just a great touch.
Any chance you could explain a bit how the Sledgehammer works? You keep track of your charge with a d6 and each charge spent increase your weapons die. However, Slayers only uses d4, d6, d8, d10 and d12. So charging past a charge level of 4 wouldn't increase your die size right? and if you take the Eager advance you increase your Weapons die to 1d6, so then a charge over 3 wouldn't do anything, correct? You still get to double your damage though, so it would still be worth it if you can charge up that long. Or am I just reading things completely wrong?