Ok, I get that It looks cool, but otherwise WHY do you suggest this, OP?
As someone else said, it would be rather odd to use this as an opportunity for spear/shield users to get another attack direction. What would the target do to defend himself, do an up-block? I'm not saying it's impossible or anything, but it breaks the idea of "stabs are blocked by down-block".
Perhaps switching to overhead spear mode would alter the weapons stats, and thus make the spearman more useful in 'X' situation. If it shortened the weapon length but increased the speed, perhaps it might serve as a 1-on-1 mode for "hoplites". If this is case, it should still be blocked like every other stabbing attack.
Whether this weapon mode granted a stats alteration, or a new attack direction, I agree with ArchonAlarion in that the weapon's attack angle should change to fit the animation, and thus allow safer thrusting over teammate's shoulders (stabbing over their head would be ridiculous, though).
I sort of support this suggestion. Playtesting would be required, derp. Also, I more support the idea of a different attack angle + stats alteration when in overhead mode, rather than forcing enemies to block a stab with an up-block.
