When you become Charged with Light, nearby allies also become Charged with Light, if they are not already. +20 Mobility.
How to get Powerful Friends Mod in Destiny 2
The Powerful Friends mod can be bought from the Obelisk: Nessus for 10 Mod Components when the Obelisk’s Resonance Rank is at 3 or higher.
Use of Powerful Mod in Destiny 2
In the game, when the player becomes Charged with Light, nearby allies also get Charged with Light, if they aren’t Charged.
Another benefit of this mod is active when at least one other Arc mod is socketed into the same piece of armor, and gives the character wearing it +20 Mobility.
A brief discussion about the mod on Reddit can be found below.
Powerful Friends Mod from r/CruciblePlaybook