Only got my first energy weapon now. It deals 18-28 Energy + 18-28 heat damage, which is greater than my .44 magnum revover, however, energy weapons run out of energy really fast. Since my cyro psi abilities are awful against robots, this sidearm is IMO better than my .44 magnum and I honestly loved how underrail seems to implement energy weapons. Laser ones are the "fastest" and the most accurate, however, the low damage ones. Plasma is similar to large caliber firearms but produce plasma require a lot of energy, so after few shots you need to "recharge". Electricity pistol is the "in between" however, electricity is rarely resisted.
I an building a cryomancer, which has some other types of psionics, but focus on cyrostasis and cyrokinesis. My stats are
STR = 3
DEX = 3
AGI = 4 (5 with equip bonus)
CON = 6
PER = 5
Will = 11
INT = 10
Lv = 10
Cryokinesis is dealing 29~48 cold + 21~33 mechanical damage. Underrail did such a amazing job with firearms, this is clearly one of the best RPG's ever.
I also running a full PSI build and didn't use firearms once, I use combination of HE/EMP grenades and Electrokinesis against robots.
A fun fact that can make the game much easier for you, you can stealthy take down enemies without alerting the others when I discovered this it changed the way I play the game.
Go into Stealth pick a enemy (or group if you can kill them in single turn) hit enter to go into turn based mode and cast Cryokinesis twice then Premeditation and cast Cryokinesis again, usually is enough to kill a single enemy then walk away, it will end the turn based mode and no enemies is alerted, for some reason PSI abilities are considered silent attack even with Psychokinesis but using guns or grenades will alert the other enemies.