Sorry for spoiling your fun, but I really don't see a reason to buff long spear vs. infantry, it is already one of the best melee weapons in the game.
Sure the overhead thrust is quite obvious to spot in a duel vs. a pikeman, but pikes have never been an issue in duels, and this would be a significant buff for them in group combat, which is their main turf.
Couching pikes (standing still!!!) sounds awesome though, just as long as it doesn't get exploited to death (if it staggers at low speed i.e infantry, it would make for insane camping).