Chrysander was the greatest general who ever lived in the Borak Empire. It was he who led the conquest of the barbarians of the west, he who subdued the great rebellion of the wine-drinkers, and he who won the impossible victory against the dwarves at the Battle of Broben. Possessed of a brilliant military mind, he was a hero of the Empire, and its most beloved citizen. And so, when he lay on his death bed, the sorcerers of the Empire turned to their magic and encased his mind and soul within the confines of a magic sword, that he might eternally lead the armies of the Empire to glorious victory. And he who wielded the weapon would be their warmaster.
But they overlooked one thing. When the mind is transferred into other receptacles, the transfer often magnifies or twists the personality, and for all his grandeur, Chrysander had one great personality quirk - he liked the ladies.
In many places, this would not have been a problem. But the Borak Empire was notoriously male-dominated, and they had now placed their future dreams into a sword which refused to be wielded by anyone but an attractive woman....
Chrysander (the sword) is a powerful magic blade in its own right (imagine a +4 or +5 in D&D terms). More powerful still is that it contains the mind of Chrysander (the general). The blade is capable of speech, but does so rarely, preferring to interact telepathically with its wielder, in a sort of mild possession. During this, the wielder retains control over her body, but gains great military skill and significant personal charisma.
In addition to this, the wielder, in theory, commands the armies of the Empire.
The Empire is unsure what to with the blade in its cultural environment, so it has locked it away in some treasury or tower. Just perfect for some unsuspecting PC to break in and steal away the greatest treasure of the Empire (and, legally speaking, control of its armies).
Deal with the social changes unavoidable in the situation where women suddenly achieve one of the most important position's in the state, and perhaps the loyalty of its armies.
The Empire has installed some vapid woman as a puppet in command of its forces, herself under the command of menacing or corrupt generals. But perhaps she is more intelligent and sympathetic than is supposed. This is just the sort of situation for PCs to swoop in and rescue an attractive woman out of her depth from.
Some horrible evil has arisen, and only Chrysander is mighty enough to defeat it. But none of the PCs are female! Can one of them be changed in sex? Can they find someone else to use as a puppet against the menace?