You can use 3 times the DSS while your TSS still on cd. Also have the chance to crit on skill and remove your target earlier from stun effect, i had problems when fatal strike crit.. its dangerous to use it. With hammer you have better atak speed and 2nd stun, but with duals you have + 2 skills which u cant use with blunt, DSS, Triple slash. I know its better to use sonic rage since its 50 mp cost and has same hex effect, but triple slash ignores shield defense, so it gives more damage than rage, which have shield def applied.
You can spam stones while combo, better 2 charges than 0 to give extra damage.