If you're played OB, then you can only use swords, so you don't have much of a choice there :P Continue to using swords, and rank skills as needed for them as you won't even be able to save your AP for spears anyway, since we can only save 100 at a time ATM. Using swords allows for Double Crescent, which can activate gliding fury, which in return is a large damage dealer, which is good for bosses. Reason being because it uses the hit and run tactic, hit the bosses with DC, if it doesn't critical, run away and wait for opening to try again, then when it does critical, you use Gliding Fury for massive damage. Then, if Gliding Fury critical, you continue with Lightning Fury, and well, that just is beastly.
Heres the jist of it, Swords finish Bosses faster, Spears finishes Mobs faster. If your looking for style though, go with spears. (I would like to also add that in KR, the current highest damaging weapon for Lann is a Dual Spears, and the are actually two of them, here is the easier one to obtain).
[Image: http://heroes.gameabout.com/uploads/heroes/info/item_shot/2010081804394185838.jpg]