How much Damage would a Lightsaber do in D and D?

[Tyndmyr]

Okay, so it's an exotic longsword that takes extra practice. Double bladed swords and spiked chains don't have a chance to harm nonproficient wielders, though, so why should this? If what you want isn't reasonable in the system you're porting it to, why bother? Do you just want an overpowered weapon that disintegrates on contact?

This.

Also, yes, I agree that corrosive does model it more closely than brilliant. As for exotic, katana actually covers that nicely, and given that lightsaber combat was originally modeled on katana combat....it's terribly accurate. For non-standard lightsabers, feel free to use a different exotic weapon.

Omni-directionality isn't really a big thing. Hitting with the edge is extremely easy to pick up with a sword. The only difficulty is really in the parrying with katanas....but that's not even modeled in D&D, so it's not a worry.

I'm not gonna get into all the star-wars anti-lightsaber plot devices that have come up. Suffice it to say, there are a few of them.