In the beggining, I'm not sure about the hoplite balance atm, so please, do not rage if you think that it will ruin the game. Just tell that it would make those too OP. (And sorry if this idea was already given - used search option, but in that case it means that I cant use it correctly)
All right, so this idea I took from mod called "Rome at War", where plaing as a greek hoplite you could swich your spear "mode" (attack) by pressing x - it made feinting impossible, but allowed at least to suprise your enemy or just have a better dmg in the close combat.
How can this vary the fighting style? First we must think how we can differ that overhead from "normal" stab (feel free to contribute). I think that we can keep the normal stab as it is now - good range, sucks at face-to-face combat. Overhead though, could work like some sort of "dolphin style" attack (a bit as it is possible in NW), which would allow hoplites to stay dangerous even when brushing enemy's chest.
Generally this would be a buff for hoplites, still I'd like to see that, because of historical and realistic aspect, which allowed such things. Even if hoplites shouldnt get a buff, it could be implemented, and balanced by nerfing damage/speed/range/animation/etc.
As I said before, feel free to contribute, every point (written in a polite manner) is precious and valuable.
Cheers
Matim