Anyways, it isn't meant to be your only weapon. If you didn't come across any others and still made it to the last boss, well, that is a testiment to how good it is.
Or rather, a testament to how good a boarding party is, since that's what won 90% of my battles.
Anyways, I want to also point out that the Glaive beam does 3 damage (-1 per shield, so generally 2 damage) per room, can hit 6 (?) rooms and is on a 25 second cool down. It takes 4 power (and 4 weapon).
Why would it only average 2? I mean, maybe you'll occasionally lose the tail to the shield popping back up, but that's it. And that's assuming you're firing willy nilly nilly instead of coordinating your attacks.
The Arty beam does 1 damage (full shield penetrate) per room and can hit a lot of rooms and with only two upgrades is on a 30 second cool down. It takes 3 power and zero weapons.
The cost of the beam is on par with the cost of weapons. Except spending the equivalent amount on weapons gives a much higher damage rate, and boosts the effectiveness by doing targeted damage to sections that will disable the enemy ship long before it is destroyed. And you don't know if it will hit a lot of rooms. It could just two! (and consistently will only hit 2 against certain enemies) You can't target sections, meaning the damage it does is significantly less valuable to boot. I'll take 3 damage against the target of my choice over 6 random damage any day of the week, thank you very much.
I think you just had an extremely unlucky run.
Well, duh. But with most of the other ships, even a relatively unlucky run would have left me in better condition. To be honest, if I'd ignored the art beam entirely and just focused on gearing up the first few sectors, I'd have probably have won this one. (Which I didn't do, primarily to get the achievement for not upgrading weapons) But that would have been despite the ship, not because of it. Any other ship in the same situation would have better offensive weaponry to start with and better final defensive capabilities thanks to the cloak.
Obviously, it's possible to beat the game with it. It's not particularly hard to beat the game with any of the ships. But this is probably the one that helps you the least towards that goal - except (and this is, in m mind, the real benefit of the ship) the varied crew and easy unlock provides an early opportunity to unlock other, better ships, thanks the ability to take on a lot more blue answers throughout the course of a campaign.