I got the impression from the game that one of the benefits of the spear is the ability to throw it, but how?

I believe that one can throw weapons using the boomerang skill, but does this apply to any melee weapon? And, I got the impression that the spear was exempt from this, is it? Or, is it merely that the spear works better, meaning does more damage, using the boomerang skill.

Please let me know,

ELB

Thanks.