Super-gadgeteers whose inventions only they can use

In many superhero comics, the main role of the genius inventor is to go into combat with his own inventions. This carries a serious bit of fridge logic: wouldn't it be more effective to focus on outfitting allies whose powers are more directly useful in the heat of combat? Or outfitting a small army with gadgets?

One answer to this question is to make it an explicit rule that only the inventor can use his own inventions. This might be because the inventions don't "really" work, they're just a focus for the inventor's subconscious super-powers. However, I think it's more interesting if, once technology gets advanced to a certain point, it just gets very difficult–perhaps dangerous–to use. Like, you could hand over control of the nanoswarm to a special forces operative, but sooner or later he'd screw up and it would go out of control, devouring everything in sight.

So how to model this in GURPS terms? I've looked for an advantage limitation to make criticals worse, but can't find anything. Also, I want a way of doing this that doesn't make these gadgets more or less generic advantages. So maybe Signature Gear with a special limitation called something like "dangerous prototype"? Perhaps a heavily modified version of "uncontrollable" applied to Signature Gear? Other thoughts on how to do this?

Super-gadgeteers whose inventions only they can use