Portable Laser
It’s exactly what you think it is. Probably.
Craft lasers
 Lasers are a powerful thing. You know that they emerge from high-frequency redstone power, but even so they never seemed to affect physical things, unless they're sitting inside a special Obsidian Table... That is, until today. While playing with Blaze Rods the other day, you actually placed one too near a working laser, and, just like that, got yourself on fire.
 After jumping in water, you got thinking. And here's the result: When near Blaze Rods, Lasers will set things on fire. While weakened, the beam can still power Tables.
Now this calls for some experimenting. Now that you know that this is a thing, you want to carry one of these with you at all times. So why not do it? You take a regular laser, add Blaze Rods for the fire, a Diamond and a piece of Glass for increased focus (thus more damage), patch it all up on a Tool Core, and that's it.

It is glorious. You can damage anything that lives AND you can craft Silicon-based items on the fly! What more could you ask?