Caster, perhaps? She is known for all of the sacred and ancient treasures she's managed to steal, and she doesn't seem like she'd either be going around assassinating people or particularly getting into fights by choice. Her greatest Noble Phantasm would be to steal the Noble Phantasms of others and gain the ability to use them as her own.
the real Carmen Sandiego would, of course, steal the Heroic Spirit's stash of stolen Noble Phantasms while she wasn't looking - and they'd work for her, too, partially because because they actually are hers, and partially because "finders keepers" is a big part of what makes the Heroic Spirit's Noble Phantasm go.
There'd also have to be some sort of noble phantasm around concealment.
the real Carmen Sandiego would, of course, steal the Heroic Spirit's stash of stolen Noble Phantasms while she wasn't looking - and they'd work for her, too, partially because because they actually are hers, and partially because "finders keepers" is a big part of what makes the Heroic Spirit's Noble Phantasm go.
There'd also have to be some sort of noble phantasm around concealment.