So, most mods that had "Charge speed" or "charge damage" have now been replaced with "Channeling efficiency" as a stat.

What does Channeling efficiency do? When it says "+30% Channeling Efficiency", what exactly is happening? Does it mean it costs less energy per melee hit while channeling, does it mean I get more damage out of channeling, does it have any other effect?

2 Answers

Channeling Efficiency reduces the cost per hit while channeling (holding left mouse button while having the sword equipped).

Base cost is 5 energy per hit (misses do not use energy), minimum energy cost is set to 1 Energy per strike, so even if you should get 100% channelig Efficiency, you can't get below that cap.

Also not that you can gain a damage multiplier while chanelling - ever 5 consecutive hits earns you a damage multiplier of 0.5 (I don't know if there is a cap).

Source: Warframe Wikia

Warframe forum

2

Channeling happens when you hold down the left mouse button while in melee mode, and (at base) converts 5 Energy into extra damage on your next melee hit.

Channeling Efficiency reduces the amount of energy each hit consumes to a minimum of 1 Energy per hit, so "30% channel efficiency" would mean your attacks consume 5*0.7=3.5 energy per strike.