I'm doing uni readings right now, so I can't really pay full attention here >.> The Laser Cannon may not be the only thing you want later on. The overheating means that you might want to think of suitable companion weapons to fire while it's cooling down from the overheat. Superion used a railgun, there might be a few other viable options too.
Anything interesting that's cheaper. I'm thinking about trinity, black stars, or maybe second railgun
In PvP, Trinity and Black Stars are both incredibly powerful. Black Stars probably has more range than the Trinity, but the Trinity's faster rate of fire probably makes it more dangerous at closer ranges. The second railgun is quite powerful, but possibly a bit hard to snipe with. That being said, there's some VERY interesting things you can do with it when you combo it properly, particularly when it's paired with the other sniper, and possibly even when it's scoped in. Alternatively, if you didn't see the link on the Freyr forums, you can combine it with a few other weapons into a freak combo like so. TL/DR: The Trinity is probably the most effective mithril weapon for PvP that you don't already have, closely followed by the Black Stars (latter is more powerful, but fires slower). Having two railguns will let you do some crazy combos if you know how to play around with them.
Which one would you get undead for the fun of it Trinity is the most useful Black Stars is effective with Cyngi Second Sniper is powerful with other weapons like the first railgun
"TL/DR" means "Too long/didn't read", so something like "to summarise" in effect. Just in case you thought "DR" meant "Double Rages"