Tongue of lyssa and the Shining Blade Oath

So if you play through one of the Caudecus manor dungeon paths, you'll find a task to save a Seraph soldier whos been taken captive. Apparently the bandits who work for caudecus have access to an item called tongue of lyssa which forces whoever its used on to tell the truth and give up any secrets if the right question is asked of them. They used it to find and capture the seraph captain you have to save.

If this item tongue of lyssa exists in lore, and cauducus and his cronies have access to it, whats stopping it being used on any member of the shining blade, making them give up SB secrets and then die??

If too many die, the rest hone in on their position and slaughter the WM. That, or, before S3, being revealed at all

First off, you have to capture the Shining Blade member before you can use the Tongue of Lyssa on them. Second, I was under the impression that before you can reveal the secret, the oath kills you. If the "bandits" knew about this trick, they could try and kill off all the high-ranking Shining Blade members, but as I believe the relic needs to touch their tongue to activate, that's not as easy as it seems.

@Rognik.2579 said:First off, you have to capture the Shining Blade member before you can use the Tongue of Lyssa on them. Second, I was under the impression that before you can reveal the secret, the oath kills you. If the "bandits" knew about this trick, they could try and kill off all the high-ranking Shining Blade members, but as I believe the relic needs to touch their tongue to activate, that's not as easy as it seems.

Basically, this. They need to have a prisoner to use it, and the result of combining the Tongue with the vow seems to be that the one being interrogated dies before they can spill their secrets. Which is a state of affairs the SB seem to prefer - one mentions that it's a convenient way to die before being tortured, for instance. Once the bandits have a prisoner whom they can use the Tongue on, it's probably already within their power to kill the prisoner if that's what they wanted.