I've tried the executive Sharpy and mods to ink pens to swap out the plastic parts. Overall, it hasn't been working in retail. It's another pen that I've got money in, which is commonly borrowed and all too frequently kept. Not loaning it is a serious breach of etiquette, too, which presents sociological flags. It's already hard enough not loaning the clipped knife in my pocket - but I'm not letting a Boker Magnum or SnG walk out the door for someone to pry a fuse or turn a screw with.
Tactical pens that look like they could survive an artillery strike seem to be the fashion, Kershaw had a combo kit this last Xmas. Once I got over the cool factor, I decided they are too high profile and an aberration, like four wheel drive trucks with raptor tooth grilles.
In the spirit of testing, I'd hammer them thru 2x4's, car hoods, or pick up some calf skulls and post the pics. Me, I'd just grab the ink pen I do have and use it on a soft target - but I would also be in such a clueless state that an aggressive predator with ill intent was close at hand, I might not be able to do anything in time.
I'm out shopping, wonder how many I can "borrow" for testing? Hmm. Haven't ever seen anyone with one, might present a difficulty . . .