I've been away from the game for awhile and decided to give the new beta (1.1.0) a try. The primary way to learn new weapon parts is to smelt down captured weapons. It used to be that when you smelted down a weapon you had a chance to learn a random weapon part. Now, the part you learn can only be of the weapon type you are smelting. Okay, that sounds logical, but the problem is that there are many weapons that you don't capture very often. You get tons of one handed swords, one handed axes and spears, but you almost never get two handed axes and swords, which makes it very difficult to learn new parts for those weapons. I think they should go back to giving you a chance to learn parts for any weapon type, not just the one you are smelting.