What about:
Swipe - U
Rare
Instant
Text: Gain control of target non-creature artifact with a converted mana cost 2 or less.
Being an Instant makes this card stronger, at the same time the 2cc limit achieves the effect of being able to swipe signets, moxen, and many other accellerants they would print.
I agree with the smaller connotation of the name. It changes the card's ability considerably though, as it changes from a card which is generally useful in many different ways against decks like tron (Early Mindslaver? I think you mean my Mindslaver...) to one which is used in a very narrow manner (namely, an extra mana hoser, though this would probably be the primary means of its use anyway).
I think this is probably a better idea though, as it does have interesting effects on other formats without being broken - it hoses the artifact lands (which generally is okay, as the only deck which really exploits them is Ravager Affinity, and no one feels bad about hosing that particular deck) and also works against decks like TEPS and Dragonstorm, both of which rely on a card which resolves on their upkeep but which they "go off" with during their main phase due to sorcery speed spells. And in Vintage, you can have all sorts of fun with it.
Cost it like this. At XU or U, it's better than Annex in Standard.
That's hardly tragic, given that it doesn't do the same thing. Its better at hosing tron decks (maybe... you can't steal tron pieces with it, after all) and Dragonstorm, but worse at hosing anything else, and is completely worthless against a lot of decks in standard which don't use signets at all.