Boss Weapons are much like Default Weapons in that they're immune to Maims. This is because Bosses are supposed to get stronger through the course of the battle, rather than weaker. I think that doing that would have been a good move. The one problem with Boss Weapons is that they're a tad repetitive and, even when the Boss has more than one, there's not much reason to not use the best one for your build.
Unless the Boss has some kind of offensive Upgrade, all you have to do is be able to resist or stay off the range of their primary Weapon and you're good to go for the whole fight. This makes me think that they should have been more like Boss Upgrades: Perhaps Boss Weapons should've had a bonus Advantage to all attacks for each level of Threshold lost, much like Default Weapons with The Beast. Perhaps they should gain extra abilities instead. I don't know, something to break up the monotony.
The concept for this weapon is a Melee weapon that prevents PCs from getting away. While the flavor works well for monsters of larger size than the PCs that can easily immobilize PCs, it is rather weak mechanically. I considered making it just freeze a PC in place, but that just wasn't fun at all. Instead it halves Speed, which is a big deal for some builds at least, and has an extra Advantage when attacking. It neither hits for a lot nor does is the debuff particularly strong, but it isn't terrible either... It is just kind of average. This probably should have been Crippling.
Healing yourself for 5 with every attack (or at least every attack that lands) is quite strong. If I had to choose one Boss Weapon to call the most generally useful one, it would be this. It doesn't strike multiple targets and it doesn't debuff, but healing half a Threshold Level is always nice.
Burst is a really, really good ability and that becomes evident when you pair it with long range. This Weapon needs Systems to be useful, but a mere 10 MP is already a Range of 5 which is enough to hit everyone who isn't packing some kind of long range Weapon. It also doesn't cause friendly fire, so this is right behind Merge in being always useful. Good think they all work flavorwise for big, hulking monsters, huh.
This does a lot of damage in a sizable area of effect. The self damage aspect seems like a downside until you realize it can be used to trigger Boss Upgrades. Pair it with something like Bullet Hell and you get full control over triggering it, damaging as many PCs as you can cover in a Blast (5) area. That's a very big area, by the way, so it should be most (if not all) of them. It's not the easiest Weapon to use in the world but it's a good tool for GMs that want a little extra control over their Upgrade triggers.
The idea for this is the archetypal big bad guy who just raises his hand and ragdolls people around like a Jedi. This is the first ability in the game that forces others to move and introduces the 'rules' for being slammed into other units or into impassable terrain. The expansion would use this a lot more and make the values a balancing factor so that each individual ability had its own contact Damage modifier. The variable energy cost is for builds that use energy to attack but expect to have their energy debuffed, so they still have an use for their remaining Energy with their backup Weapon.
Extremely nasty on sniper builds, whether they're the stationary kind that stay in a well protected location or the hit & run kind with the appropriate Capstone. It basically forces a single PC to stay still or take a bunch of damage and likely miss their counterattack anyway. It's okay in other builds too, simply because the debuffs are solid. One of my favorites.
This is the most effective debuffer Boss Weapon in the core book. It doesn't care much for damage, but the debuff is very mean and covers a wide area of effect. The flavor is a leftover from when all Boss Weapons were biological in nature and I never came up with a better concept than "leech-like missiles, I guess?". A Boss that spams this isn't going to kill anyone, but it is going to be a priority target because the debuff is that solid.
This used to be a Blast (10) for flavor reasons (it's pretty much a nuke) which... Well, it was kind of gross, let's just say. As a Blast (5) it is a lot less ridiculous, while still being very exploitable with the snipy builds.
A Beam Line that creates Extreme and Difficult Terrain? This thing hurts. Overfreeze is a threat at all PLs, at low PLs that's because of the Terrain effects, and at high PLs it is because it is a Beam Line. It's powerful but not too powerful and I think it's one of my best Boss Weapon designs because it just always works.
The only Weapon in the game with infinite range and, before the expansion, the only Weapon in the game with a charge and recharge time. I would have liked to have more Boss Weapons that do unique things but it turns out coming up with 'things you have not done already' isn't all that easy. As for its inspiration, Final Beam is based on the classic JRPG Boss that tells it is about to unleash a super attack and you get 1-2 turns to heal/buff/defend before it hits.
And that's Boss Weapons. If I were to redo them, I'd probably take away some of the offensive power of Boss Upgrades and make Boss Weapons get stronger for each Threshold Level lost instead. Whether it is with unique new abilities or just plain giving them more Advantages, that would have been a nice thing to give them, I think.
Next: Boss Capstones.