In my opinion, Long Spear should be an enemy speed based weapon, this mean that it's damage should rely more on the speed bonus of the enemy that's running into you - making this weapon an excellent cav stopper and a nice infantry charge stopper. I guess just reducing damage would help that.
Thing about this idea is that the combat dynamics and animation.
ie As a piker, I use the mentality of my opponent against them. They come at me with their weapon, so I back away, at the same time stabbing out with the pike, if they don't block, their walking speed vs my pike driving into them causes them some pretty hideous damage, given what I've seen of their reactions in duels and battles.
The stabbing animation is a lot faster in comparison to my character backing up, on top of the fact that the other guy is running straight at me in an effort to catch my armored ass. SO they essentially spear themselves on the weapon.