Press L+R triggers after selecting spirit of the devils. Hold a brief amount of time (like 2-2.133 sec). Press A to use the upgrade then immediately mash B to cancel out of the menu. Pressing A makes the game trigger the use animation on the spirit of the devils but due to a bug the game will attempt to scroll thru the menus from the triggers being held. B exits the menu before the game deletes the Spirit of the Devils item from your inventory.
So far I haven't found a consistent method of making this work. Extremely finnicky.
In this clip, I dupe it once. Then I don't fully execute the trick completely and finally fail consuming the item.
PS: Came as a vague rumour from a Firdaus Juraimi in a youtube comment from one of jtb's videos.