Savage Fury Support Gem Error?

The Efficiency selections for Savage Fury buff appear to be redundant. The description states:

"Supports and skill, making it cost less to use. Cannot support skills which reserve Spirit"

Given that this is a Spirit buff, the Efficiency modifier renders it's use to be absolutely redundant as a selection.

Perhaps this was overlooked, or is this a feature with a future alternative resource exchange such as skills costing life/mana instead of Spirit? For now, as an early game choice, it's useless.

https://steamcommunity.com/sharedfiles/filedetails/?id=3626258325