Art thou serious?
Ye give everyone access to such a long polearm, that cavalry will be completely useless, even more than it is due to pike spam already!
...
That would require all of them using the long pike to not have another weapon... you have to drop it not like a pike which can be sheathed.
No, this is not a case of "everyone has it and cav is useless" scenario.
Hm .... i think the actual pike is long enough against cav. 
If someone wants the plain pike as a secondary with a primary use against cav, then he can use that. This would function as a dedicated weapon -- and not necessarily vs cav. I was primarily thinking of it's use as a support pikeman infantry.
I know you suggest a new weapon, but what do we use a Pike against? Cavalry, and infantry backup.
Check the longest Great Lance, it's almost as long as the Pike, maybe a bit shorter.
In melee combat, it can annoy the crap out of your foes if you are in a group.
A longer pike is not needed imo.
But still, the no overhead for the current pike is just dumb, it would reduce the usefulness of that weapon to shield+spear's.
Again I am not suggesting the removal of overhead for the current pike.
And if it is seen that the weapon is not needed, then it will be not needed. Is there any way you would change it?
I am just proposing this idea of a longer pike that is thrust only; but can't be used as a secondary so it won't be abused vs cavalry.
300-350 max length IMO. Any longer and it will simply be unusable imo.
Give it more pierce, say 30 - 33 BUT it can't be used to block. For freaking obvious reasons. Make it truly a support class
This is the kind of constructive response I am looking for.
However; I don't think it can have that much pierce damage. I have it doing 25, one less than the regular pike for a reason as it is longer. Also, what exactly is this obvious reason it should not be able to block? I must be missing it. For game balance, that doesn't really make sense and with how it is animated as it would look fine with blocking.
I thought about 350 or 375 length, but if it is under 325 length the weapon will flat-out be pointless to have thrust only, if it is only 300 length it would not only be logical to have an overhead, but it would also not have it's own role in the battlefield as the regular pike could fill it. 350 weapon length could work, and is completely realistic.
350 weapon length vs 400 -- with 350 it is slightly more usable in single combat, and takes a little away from teamwork and coordinated combat. 350 would still be fine though as a support weapon.
