From WoWWiki
Master of Arms is a general achivement.
Every class starts with at least three weapon proficiencies, and they can purchase training from Weapon Masters for two more. All classes start with training for Unarmed combat.
Strategy
- You can skill up unarmed to 400 to complete
Did Somebody Order a Knuckle Sandwich? and it will count as one of the four weapon skills you need to complete this achivement.
- It's best to equip weapons that have very low DPS and fast speeds, because your chance of skilling up is per attack, not per kill. White items you can purchase from vendors in the starting areas, or grey vendor trash items are good options.
- You can skill up on mobs far below your own level, to prevent the damage that you would take, but you will get fewer hits on them before they fall down.
- A good Place for Allaince is the stormwind stockade
What does not work
- You cannot skill up by attacking mobs that are immune to damage; for example the Traning Dummies found in capitial cities are not good for practicing your fencing abilities nor sniper skills.
Patch Changes
- 3.0.8: you can no longer skill up weapons on mobs that are immune to damage.
External links