On the fetralife wiki as a comment.
"Ds3 and bloodborne have the same method to load their maps (and the same glitches), so killing siegward just before yhorm s bossfight and changing zone again and again (run to yorshka s church, get out and get in the building as many times as you see fit) will make his slab and equipment to duplicate. IMPORTANT: don t use any bonfire until you picked up the loot. You ll mess up everything!"
If that shit's true then this man found infinite titanite slabs.