Ahoy Guru, nice to see another of the older guys gathering back here. 

Like Green, I'm not exactly seeing the problem... If I said I had a sword that turns itself ablaze because magic, people wouldn't have a problem with it, despite it being even more impractical than a vibra-blade would be. I don't think simply saying "this sword functions with false science instead of false magic" should make it completely exempt.

After all, characters using such weapons usually have reasons behind why they're unaffected by their drawbacks (i.e. a fire-blade user just happens to be heat-resistant), or some other pseudo-technology that makes that weapon viable for them. Yes, the effects of a weapon need clear explanation (just like fake materials and magic systems), but while their method of doing so should be stated, 'semi-realistic' fights simply can't happen without some form of handwaving there.