There once was a Sacrificial Dagger and a Blade Of The High Priestess and both were sentient and shared the same owner.
At first while one was equipped, the other would get extremely jealous........ and they'd take turns as for some reason their wielder wouldn't wield them at the same time. But then on that fateful day, they both stopped being used and were placed into the bag of holding together where they only had the company of eachother to keep. As they sloshed around in the bag of holding and only had eachother for company they soon grew to better know eachother, then they started to like eachother and then they simply fell in love. One day the ingredients bag's cannith essences began to overflow and spill out into the bag of holding and the owner of the two daggers for some reason placed a minimum level 29 dagger with no magical properties what so ever into the bag. Is he seriously planning on crafting a dagger to replace the role we once held? Said the Sacrificial Dagger. I doubt it, if I had to guess he's just trying to make use of some of those cannith essences he has sloshing around in here replied The Blade Of The High Priestess. As days went on, their owner undertook more and more challenging quests and now his bag's content was overflowing with even more stuff, the maintenance was atrocious, there were a bunch of Khyber Dragonshards of every shape and size, a ring granting bonuses to conjuration DCs and more. One day their owner was bleeding so badly it started seeping into the bag of holding somehow, the The Blade Of The High Priestess then gives the Sacrificial Dagger a piece of parchment and says, here's read this, there may be nothing we can do about all of this blood but at least there is something to read to take your mind off of such and just as the Sacrificial Dagger was finishing up the read their owner was knocked down by an enemy slamming the two daggers together igniting a magical spark from said slamming that then traveled into the cannith essences and then being absorbed like a sponge into the blank dagger all the while their owner FAILED his save on the trap the soul scroll that was just read. The soul gem was then placed into the newly formed magical dagger that resulted from the spark of miracles that occured and the loving couple (That happened to be sentient daggers) and so their owner was now essentially their baby....... he did not like it at first but after centuries or patronizing him and tormenting him he eventually lost his mind and became as their child would be according to their mindsets.