The Focus Energy mod increases Channeling efficiency and Script error: The function "Proc" does not exist. damage on melee weapons by 10% and 15% per rank, at a maximum of 40% and 60% at rank 3, respectively.
It should be considered that Focus Energy stacks with Shocking Touch and Voltaic Strike if more electrical damage is needed.
While Reflex Coil and Focus Energy combined will total 100% channeling efficiency, Melee Channel has a minimum energy cost of 1 Energy per strike, translating to an 80% Channeling Efficiency cap.
Trivia
Previously, the in-game description of this mod incorrectly stated: "Convert 10% of energy used to Bonus Damage on next Melee Attack. Store up to +0.2 Bonus Damage"'