"How do the blade runes light up and why did you make it from wood?"

The blade is only 1/2" thick. There are several reasons I made the blade from wood (kiln dried, select Pine) those include rigidity, durability, light weight, easier to finish quickly.

Blade runes in steps:

After shaping the blade I cut a 1" x 6" hole in the blade with a jig saw.
Added led rope lighting to the inside edge of the hole. This makes the leds glow inward and helps eliminate hot spots.
I had Vertvixen 3D model a 1" x 6" x 2mm thick inlay plate that had the runes knocked out of it. The inlay fit snugly inside the first 2mm of the previously cut hole on each side. (Thanks to MaCo Creative for the final inlay 3D prints.)
Several applications of filler and sanding to smooth the inlays and make the seam between the 3D prints and wood disappear.
Primer is the final test to check for seamlessness.
Finished blade with paint and lights.

* All of the 3D elements for Frostmourne were created by Vertvixen.