...No, really. That's all you need to know.
(not to be confused with SWORDMAGE, which is a fighter with a magic sword who totally isn't weeaboo because he's in the Forgotten Realms book rather than the Book Which Won't Be Named)
Okay in actuality they rely on "maneuvers" (read: Martial Magic, hence weaboo status) that they prepare, each with a different effect,not unlike another character class, but instead of preparing spells you take a five minute stretch, a stretch that somehow allows you to walk through walls, Rip people in half, and even straight up teleport. They were what happened if Wizards of the coast thought "Hey let's give Martial classes actual usable shit"