TL

R
When choosing weapon, you must consider:
1. Type (light, hand, 2h)
2. Base damage
3. Speed
4. Critical
5. Elemental damage
6. Additional bonuses(like vicious)
Explaination:
You probably want to use reliable weapon, so:
Ad 1: this will allow you to use specific skills, that your character learned
Ad 2: this will determine how well you can penetrate armor, how big will the critical hit be, and it has the biggest influence on DPS
Ad 3: important for DPS (not really helpful against armor), and stunning or other effects your hits can have
Ad 4: determines how often you can deal extra damage, but it's not very reliable, that's why it has fourth spot
Ad 5: good when cleaving, good when the enemy is weak against it, useless when the enemy is immune, and harmful when the damage is absorbed!
Ad 6: Additional bonuses have specific conditions for activating. Those are nice to have, but you'll rarely have use for those