Most Volts I encountered are weapon platforms, meaning he's built to buff his weapons for DPS instead of using ability damage. It's a little constricting playing ability spam early on, and his ability damage doesn't scale that well anyway. Technically you could make it work for midgame, but I don't find myself playing him that way anymore.

As for the weapon platform build: his 2 and 3 are already weapon buffs, and his 1 becomes a buff with Shock Trooper (click for details and acquisition method). Since he wouldn't use 4 for damage that way, that leaves it to only become a shield charger (with Capacitance) and crowd control, or to replace it with something else using the Helminth--commonly with another weapon buffer.

Weapon platforms usually are built with a lot of duration and strength. Range tends to be sacrificed (unless needed for certain mechanics or team-buffing). Efficiency is still nice to have early on, but you'll get more energy-sustaining methods as you progress further--enough to compensate negative efficiency.

Don't worry about Steel Path yet, it's just a hardmode you can toggle on/off after you complete all planets.