I suppose lots of things are possible. IMO any sharpening rig robust enough to carry with you in a PSK or as EDC will probably be heavier than simply carrying a second blade. Anyone that carries both a knife and a multitool probably need not worry about maintaining their blades. And in a pinch many of them have a file that will work for rough sharpening.

That said, DMT makes some little diamond cards the size of a credit card. That might be worth the weight and expense if it fits in your wallet.