I agree, FK needs some love… here I wrote my thoughts.
Anyway I think the same thing: “aggressive” talents (like more power or attack speed) make FK a weaker Merc… BUT this is a complicated speech.
Imho we should start from those things that could give to FK some particularities when compared with IB (like more agility or staggering capacity)… a couple of good examples could be Valiant Charge (ult), Staggering Force and Counter Punch (talents)… but these abilities have serious problems that should be fixed (for more details read the linked thread).