We all love our Impalers, Halberders, and Sentries, do we not? Their pole-arms or spears are quite good at defeating the Calvary menace, saving our infantry from the hooves of death. Remembering back to watching Lord of the Rings i recalled those gigantic spears that they seemed to wield that seemed impossibly long. However, the more I thought about it, the more useful they seemed, seeing how they could easily be braced against the ground when a Calvary charge was incoming.
What i propose is to give spear units some of these long spears, but in a gradual way. The first row should retain the same ones they already have for short range. The farther back they go however, the longer they should be. This would allow the majority if not the entire squad to be able to attack the front line attacker at the same time. Some may say this would imbalance it all due to their abilities. But, if sentries are doing this, they wouldn't be able to use their knockdown past their first row because the spears are just too long. As for the Impalers leap ability, only the ones in the front/sides would perform it as well.
As is, other than their abilities, they tend to be unable to put much dmg on any targets at all while retaining any form of defensive position. Spear men historically have had great defenses that many found hard to break due to the fact that the closer you get to them to break it, the more you would be in range of.
"To underestimate a Goblin Horde is to stare into the face of Hell and think it to be heaven." ~ Svulnar, The Goblin King