The original Batman build was created when the level cap was 12 - Fighter 7, Paladin 3, rogue 2 and was built based upon a single random item drop, a ring, that was very expensive on the auction house. I forget what was on the ring exactly, but remember guilds pooling money to buy one on the auction house.
The build evolved when the level cap was 14 and died out at 16 when they "fixed evasion". At 14 the ring wasn't a mandatory requirement and build became more common.
The Batman build was replaced by the Valkyrie build when the level cap went to 16 which was a TWF Pally 12, Rouge 2 (6), monk 2 which existed all the way to Shadowfell Conspiracy, at which point it was 12 Rogue, 6 Paladin, 2 Monk was the heroic levels. They actually nerfed TWF twice and eliminated Wounding of Puncturing because it was so effective.
A version of the build made an appearance with the release of Harper (strategic combat line) with Update 23.
Variations of the Batman and Valkyrie builds show up on the Hardcore Server as somewhat self sufficient characters.
