Are lightsabers possible?

Femtosecond lasers ionizing air could create a blade looking glow shaft of firey light - but they'll all be blue unless you pump a gas into it I guess.

Taser-type weapons have also been made into gloves and "blast knuckles", which are pretty intimidating. I know of a vigilante who did some interviews, he said that usually just lighting something like that up is enough to scare off would-be attackers. I'm sure with some modifications that could be kind of like force lightning!