I think "Misadventure" usually refers to you causing your own death through a grenade or rocket launcher. You weren't using a Touch of Malice at the time, were you? Dying from fall damage, falling out of the map, being flung against a rock, etc, usually causes the "Killed by the architects" reason for death to be shown. I could be wrong, but it's early morning and I can't clearly recall exactly.

if it was in cabal territory then its probably a phalanx