If I had a fighter that was proficient with whips, could I equip a Kumade (which "doubles as a grappling hook") and take the feat "Hook Fighter" to "treat it as a two-handed melee weapon with 15-foot reach" (if I attach "at least 10 feet of rope or chain" to it) "that deals piercing damage equal to a heavy pick of its size and that has the disarm and trip special weapon features", including the x4 critical multiplier?
+If I can would I need to take weapon specialisation (kumade), (grappling hook) or (heavy pick) to increase its damage?