spears...

[ViktorTheCrazed]

how can i know which spears are one hand?

[Lamix]

take a look at polearms http://forums.taleworlds.com/index.php?topic=132836.0
any with the can use with shield, i'm assuming thats what you mean and not the one handed skill.

[ViktorTheCrazed]

it says
Long Awlpike: Overswing, Thrust, Can't be used on horseback, Can use with shield, Penalty with shield, Carried on back.
but i cant use it with shield

[Trael]

it says
Long Awlpike: Overswing, Thrust, Can't be used on horseback, Can use with shield, Penalty with shield, Carried on back.
but i cant use it with shield

Based on what i have heard in game and forums, thats outdated info. Based on my observation of chat long awlpike got changed in last update to "cant be used with shield"

[Spawny]

True. The long awlpike can't be used with shield anymore.

For the rest, all polearms with the"Can be used with shield" are used in 1h when you have a shield equiped.
It does use polearm proficiency though. Unlike the bastardweapons which use 1h prof when used with a shield.