Originally Posted by Semp Pi
For the "Keeper of the Armory" achievement, you have to complete all weapon challenges.
One available weapon is the power sword, which can only be unlocked for use by completing the first level of the WH40K Kill Team XBLA arcade game.
Has anyone played enough to know if this weapon is required for the achievement? I liked the kill team demo, but to force people to buy it to obtain this achievement is a bit upsetting.
update: You can work on the weapon challenges for power sword without unlocking it. You can steal the loadout of the player that kills you. If you get killed by a powersword, make sure to take the loadout and try to get kills. Alternatively, play private matches with someone who has it unlocked and farm the kills using the steal loadout method. Obviously option #2 is much faster.
I can confirm the power sword is NOT needed for Keeper of the Armory.