Item Duplication Exploit (Can be used on boss souls)
This is a glitch that can be exploited to duplicate items* that you want. Using this glitch is not recommended if you want to still have a challenge in the game.
1) Make sure you have the nexial binding equipped. 2) Buy an item (I recommend crescant grass, only need one) from Blacksmith Boldwin. 3) Walk away from Boldwin, DO NOT EXIT THE SCREEN. 4) Use the nexial binding, but do not select okay to use. Pause the game after hitting the button. 5) It won't actually pause the game, but the game thinks it is. Now, talk to Stockpile Thomas. 6) Select the item you want to store and select okay. 7) Quickly press circle or B to abort the transportation.
And there you have it. You can talk to Thomas and get your items out, it gives you two stacks of 99.
*This only works on consumables. It doesn't work on ores, armor, weapons, arrows and bolts, or rings. It also doesn't work on ephemeral eye stones.