Polarize Hull is a great way to break tractor beams if fighting Borg, Breen, or Romulans, and lets you save the tac slots instead of running Attack Pattern Omega since you can put PH1 in an ensign slot. Beyond that it really depends on what you want to do and what other powers you have elsewhere. And you already have a Sci Team and Hazard Emitters, though I'd bump the HE up to 2. Maybe add Transfer Shield Strength 2 if you want to be able to heal teammates.
One thing to really remember is that with only 6 weapon slots, you will probably have the weakest direct offense in a group, since only a few sci powers do significant damage. On the other hand if you stack on some mobility control powers or power drains, you can lock down whole groups and make them easy prey for your escort buddies. Interestingly with the Magellan, that LtCmdr engineer slot means you can add Eject Warp Plasma 1 with a Matter-Antimatter Specialist to a de-power/crowd-control build. Stun with the Plasma so they can't run from a Tyken's Rift, or toss it on after a Gravity Well and keep a cluster slowed and vulnerable (plus now on fire!). Or roll into a clustered/stunned group and blast them with a Photonic Shockwave, Tractor Beam Repulsor, or Charged Particle Burst. And lastly I get a lot of use out of spending an ensign slot on Tractor Beam 1, just to reel in 'the one that got away' in PvE play.
There's also the confusion route, though I'm not a fan of it and haven't seen anyone use it very well (i'm sure there are some amazing guys, but they're rare). Jam/Scramble Sensors seems neat at first but in an STF it just means they ignore you and shoot a teammate for a few seconds, and in PVP its easily cleared. Viral Matrix is fun to use on big PvE enemies to screw them up for a few seconds but its too brief to be worth giving up the high level power slot.
There ARE builds to make you into a gun-bunny, but in my RSV I find tossing around heals and debuffs to be more enjoyable and much more distinct. Otherwise you're just a cruiser with a few toys and reduced weapons, or a slow escort with some extras.