I think Arm of the Destroyer should be an AoE that eats chakra (It's name is too badass to remain useless) Leave it at 50 pot but have it eat one Chakra. There. Useless skill made useful and chakra now has much more use. Just put the silence on One-Ilm Punch and remove it's form restriction.

Also, Chakra should proc off any crit at a lower rate. 20-25% would be better than what it is now (Given auto attacks and abilities). If only to make it "feel" better.