finger severer greyed out

[gamoreno94]

not sure why but the finger severer is greyed out and no longer an option to use ive only been able to successfully summon an ally once

[[MD]Fox]

works on my machine

[Dark Angel]

You can only use the Finger Severer to leave a multiplayer session, it sends you home when you're a summoned phantom and don't want to stay in the host's world. When you're the host you can use it to send your phantom back in his world.
Ofc it is greyed out when you're alone. You can read the item description in your multiplayer menu or in your inventory.
To find other players signs you need another item: the Furlcalling Finger Remedy. You can craft it in your crafting menu, needs only 2 flowers.
https://eldenring.wiki.fextralife.com/Furlcalling+Finger+Remedy