+3.5-5% Strength for 3.5s on Hit. Stacks 5 times.
+70-100% Critical Weak Spot Damage.
+14-20 Critical Chance on Weak Spot Hit until your next Critical Hit. Stacks 5 times.
You might be able to tweak this to improve it but it works for me and competes well. Its main issues are just being squishy. A good defensive melee weapon is advised, especially something with armor pen. Power Swords solve lots of problems but don't give you much mobility so your call on that, personally I find them boring. So I favor shovels and the MK4 Chain axe here.