i personally wouldnt empower the duration of fatal slash nor of bone slicer. the base duration is 20seconds which will only run out if your fighting bosses or people. and the skills will be also ready to use again by then.
for the cooldown of these skills, i think thats a better idea
im playing a different fighter then yours will be and havent yet decided on other skills (even for my own build not, after getting it to lv47 o_O), so this is all i can offer
