A more D&D-style description, though not the original (by Thomas Miller, not T$R)
CN Longsword +3
Int 17, Ego 16, Per 32
purpose: to suck souls
slay foe with soul to gain levels and full hp for levelsturns
each 3 days unfed, ego gets +1 until a killing happens
speech & telepathy (Common + wielder's languages)
detect souls 60'
haste (10 rounds) 1/day
100% resistance to charm and fear