[Broorbbub]

Assuming you're actually serious and not being sure what you mean by "us sabre rules" (do you mean olympic fencing sabre or some lightsaber ruleset that exists on the internet somewhere), I'd assume the use of a light, straight sword would quickly turn into something resembling epee fencing. Without specific rules limiting thrusts, no-one would use a cutting motion as it would be too slow.

Also, I strongly agree with the above poster, get insurance (if anyone would provide it to you). I'm not sure of the laws in your area, but if you have people performing a combat sport in the dark with equipment not properly designed for what you're doing, you're going to lose a negligence claim when someone gets injured and sues you