It is best to use dual-wield if you want to use both hands. If you use more than one type of weapon your skill gain is spread over two categories and will take longer to raise.
Weapon skill over 50 does very little. At 60 you get a new special move. higher weapon skill will shorten the time it takes to change your aim (ei: lower center, upper right) and will also increase your chance to change said aim. Grinding past 50 skill, however, does not seem to increase one's chance to parry or hit.
An easy way to gain weapon skill with [[axes]] and [[swords]] ([[longsword]] and [[huge sword]], respectively) is to cut trees down with [[woodcutting]] until 20 skill. This renders even the lowest skill fighter a fairly potent adversary to most common creatures in the Wurm universe, and offers some good [[body]] and woodcutting skill gain to boot.