I seem to remember that there was a pathfinder ranger arctype in which you can use your Weapon as your companion instead of animals or your companions.
I dont remember if its a specific archtype or just some lesser modification to the basic ranger but I was hoping some one here could point me in the right direction.
on a side note I am building a character at level 8 and am considering paying for the character to start with an intelligent weapon. though I wont put a lot into making the weapon overly powerful if there is no specific weapon companion archtype does any one have any good suggestions?