I'm having trouble figuring out how to interpret some of the weapon stats.
Fire rate and consumption are obvious. But I'm not sure how to interpret Energy Ratio and Gain. What do these two stats represent? I'm trying to figure out which weapons are better, but I don't know how to interpret these stats. Any help would be appreciated.

I found this thread which might help you out:
http://213.198.65.214/forum_DS/showthread.php?t=1565
Gain, apparently, stands for how much power you get when changing weapons. For example,if weapon A does 16-24 dmg and weapon B does 24-42 you gained 8-18 damage.