{Spoiler} Conduit.

[Blinkybubs]

What does Conduit mean on an items properties?

[The_Driver]

Just like some other properties as blood magic or pain attunement, this means you gain the properties of the keystone of the same name on the passive tree. Those properties do not stack with the keystone passives ones, if applicable.

Share Endurance, Frenzy and Power Charges with nearby party members

Conduit is a keystone passive skill that shares charges with nearby party members only (summoned minions do not receive charges).
Whenever the character gains an endurance charge, a frenzy charge or a power charge, each nearby party member will also gain one charge of the same type.

http://pathofexile.gamepedia.com/Conduit