Sunsword

From Wikihack

Sunsword is a rather useful artifact long sword. It does +1d5 to hit and double damage to undead monsters; L, M, W, Z, ghosts and shades. It also acts as a light source with a radius of 2 squares, and prevents blinding from lights. It becomes lit when wielded, and unlit when unwielded. If you kill a monster (except by stoning) which is wielding it, then it will stay lit, allowing you to use a different weapon while still having a light source.

[edit] Light Radius

The Sunsword has a light radius of two squares around the character (or monster) it's being wielded by. Compare that to the radius of a lamp, which is three.

...........
...........
...........
....xxx....
...xxxxx...
...xx@xx...
...xxxxx...
....xxx....
...........
...........
...........

X's represent the squares lit by the Sunsword.