If you need a sword with a bit of lore and a decided preference for elves, Sarastra’s Shadow might be exactly what you’re looking for. Take a peek.
Sarastra’s Shadow
Aura strong illusion CL 18th
Slot none Weight 3 lbs.
Description
This minor artifact is a keen spellstoring holy frost longsword that has a blade that appears to be made of black ice. The wielder can also invoke the dancing, disruption, and ghost touch properties once per day, for 7 rounds each, but only one at a time. The legends say that Sarastra, the elven goddess of night and magic, created this powerful weapon to give to one of her champions, Erevan, when the various powers of the Eleven Hells were encroaching on territories she considered her own. He used it for centuries to battle her enemies, but the ghoul knights of Anu-Akma finally defeated him. The sword was lost, and it was last rumored to be hidden in the labyrinth of the king of the shadow elves.
Any non-elven spellcaster that grips the sword gains two negative levels and is swathed in a permanent darkness spell until the hilt is released. If the sword is wielded by an elven spellcaster (such as a witch or magus), the caster may spontaneously cast any shadow spell that he or she is of sufficiently high enough level to cast, even if the caster does not have the spell in the normal spell list. For example, a 9th-level sorcerer, while holding Sarastra’s Shadow, could sacrifice a 4th-level spell slot for that day to cast shadow conjuration, even though it is not on his or her normal spell list. No other material component or focus is required for these spells other than the sword itself, and holding the sword never causes penalties for the somatic elements of these or any other of the spellcaster’s spells.
Once per week, the wielder may lay the sword on the shoulder of any humanoid creature and instantly lay a geas on that creature.
Destruction
Sarastra’s Shadow may be destroyed only by casting it into the fiery forges of Baal, or by exposing it to the solar radiance of the sun god Aten continuously for 24 hours.
Very evocative!
Do you mean by “normal spell list” spells known? The example you give would seem to indicate this, since Shadow Conjuration is a Sorcerer/Wizard spell. The phrasing is just a little confusing, since it could indicate that you could cast any shadow spell, whether it is on your class spell list or not. Which would be extremely powerful, and in which case it might be worth noting which spell level you would use in case of discrepancies.
I realize such quibbles are less important for artifacts, where power levels are inherently unbalanced.