Eberron Campaign based in Sharn. the PCs get contracted by an old granny elfie whose husband left her for 'a flirty bar wench.' She wants them to break into the highest bank in Sharn (possibly with help. they ARE level 6) and see what the husband did with a certain heirloom in a certain and deliver it to her for verification purposes. The old bastard took everything she had and ran away with it.

When the PCs get into the vault, however, the trap springs. They get attacked by a group that shadowed them and get framed for breaking in and jacking an object from the vault of great importance to a lot of special interest groups. They find that the 'old granny' is a young elf druggie that went insane after she herself got fucked over by somebody else; she did the job, they didn't deliver the drugs, and she's now suffering permanent insanity as an effect of her withdrawal, shuffling around Lower Dura.

Problem is, I don't know what the hell that certain item in the vault-SHOULD- be. I don't want a stereotypical mythic object (IE: generic D&D sword of aweshumez power or a robe and wizard hat), but I want it to be something... awesome. Some kind of prototype or something of great intellectual importance. That, and suggestions for how I should alter the campaign setting would be nice, if level 6 is too small for getting a party into the Biggest bank of Sharn, Upper Central. The object's going to be in a deluxe vault, but not their most expensive/most protected option (reserved for the privileged).

tl;dr: Items for placing in a vault.