Margit's Shackle in Elden Ring has a strange second purpose

pcgamer.com:

If you've been playing Elden Ring like most of the gaming world, you've probably said hello to the first pain-in-your-ass boss, Margit the Fell Omen. He's very early on in the game, and we've even had to create a guide to stop people barrelling towards him underleveled. Even though he is pretty tough, there is one very helpful item that can help you beat him: Margit's Shackle. 

Slight spoilers follow:

You can buy Margit's Shackle from Patches, located in the ravine splitting Limgrave in two in a little place called Murkwater Cave. He's technically a boss, but not a very threatening one. Players of past FromSoftware games know Patches as a recurring troublemaker. In Elden Ring specifically, Patches becomes a merchant if you spare him, and one of the important items he stocks is Margit's Shackle. 

If you're really having a tough time with the Fell Omen you can get these shackles and use them in the fight. They stun him for a short period of time, allowing you to recover or get some solid hits in. 

Or you can use them for a different purpose altogether: It seems that Margit's Shackle also uncovers illusory walls. Weird. 

As reported by GamesRadar, Reddit users have been uploading videos of their characters revealing walls with the Shackle. It seems by using it, which involves your Tarnished slamming the item to the ground, the game registers it as a small shockwave of sorts. This then strikes the wall and registers as a hit, thereby opening the way. Actually pretty useful if you want to check for walls without smacking every vertical surface with a sword. I don't know about you, but I'm always fearful I have accidentally missed a wall even when I've hit it, just in case I hit it 'wrong'.  

Yet another use for the shackle is