Alright, I won't get too deep in the details for obvious reasons, but here is the little thing I discovered...
Basically, I discovered a way to access a bank while in a quest.... only a certain quest though, this would not work with others for certain reasons... Now because of this, you could technically, with 2 people, have 1 die, and the other could take his or her soul stone, and put it in the bank, or shared bank...
Now, you may be thinking "What the hell is the point?" Well, what do you think would happen, if said person was... out of range of their soul stone for 10 seconds?...
Edited: So, I decided to test it... What happened was, after placing the stone in the bank, there was no more "out of range of your soul stone" message, no matter how far away I moved. Pulling the stone out made the message re appear, and functioned normally... Kinda cute.
Also, it's "not bankable", but will go in the shared bank, and from there, can be moved to the regular bank.