Weapon and shield is generally optimal. The defensive value of the shield generally outweighs the benefits of other styles of combat. Spear + shield has the best defensive characteristics.
Two handed weapons are sometimes useful. They do lots of damage and some of them have very nice abilities.
Dual wield is terrible. You should never use it.
Don't worry about committing to any specific weapon class. It's better to adjust your weapon based on what you find rather than what you've been putting marks into. Never overlook a much better weapon just because you've got more marks in a worse one.
Hoping to win with every class, doomed. Archer, Barbarian, Bard, Beastfighter, Druid, Elementalist, Farmer, Fighter, Monk, and ULE Priest down.