It deals 20 damage (10 hearts), or 25 with a critical attack, so it is able to one-hit-kill regular mobs when charged.
When turned off, the Nano Saber deals as much damage as a Wooden Sword; 2 hearts. It must be turned on to deal maximum damage. To turn the Nano Saber on or off, simply right click with the Saber equipped.
While turned on, the Nano Saber will constantly consume EU, therefore it is advised to always keep it turned off when not used. Strong as it is, the value of the nano saber is arguable, seeing as a chainsaw can do the same amount of damage in just two hits and is less rescouce demanding.
As with the Power Tool, the Nano Saber cannot be enchanted directly or with enchanted books.
Note: The animated blade is glitchy on multiplayer servers, Often jumping between on and off and becoming stuck on one part of the animation for long periods of time. Keep that in mind while using it on a server, As it can fool you into leaving it on when you're not using it and wasting the battery.
Note 2: There is a bug in FTB Ultimate where the Nano Saber does not draw energy in multiplayer. This was tested without Gregtech on a private server.
Note 3: When fighting the Ender Dragon with the Nano Saber, Minecraft can crash and corrupt the world.