The Keenseeker

This item appears to be a Longsword hilt.
You can use a bonus action to cause a blade of
pure radiance to spring into existence, or make
the blade disappear. You can use an action to
expand or reduce the brightness of the blade
from 5 to 30 feet.
This Magic item has the Finesse property.
+2 Radiant damage to attack rolls.
Bonus 1d8 damage against undead.
"Darkness cannot drive out darkness: only
light can do that." - M.L.King