i was thinking like this:
a + 4 weapon,stun,haste,5% chance to kill enemy instantly,5% to set time stop(for 2 rounds).....you can make d history....

my version of history:this long sword has been forggoten long ago in the time when Was Moria....it has been Forged by Balin the ruler of Moria.it has been forged with Mithril..

something like this

Anduril
Long Sword
Enchanted +4
THAC0 bonus +3
Damage 1D6 +3
10% chance of stunning the target
Vorpal weapon (5% chance, save at +2)
5% chance of Time Stop (2 rounds)
Can cast haste 2/day

Looks a bit overpowered, I would remove the Time Stop, but if you like it, I like it as well.

u can remove time stop...i dont like overpowerd weapons..except ravager+6