It's well known you can never have too much Dakka, and even though MZ+ allows you to get a lot of firepower from a single weapon, I don't feel that there are enough options to create "any" weapon. For starters, I can think of a number of iconic weapons from sci-fi the system would require the "Special Mekton Trick" generic upgrade to handle, which can be severely undercosted for what it can offer. For example, Tesla Coils would clearly be an Energy weapon, but there's no Shock upgrade for Energy weapons. Likewise, what if you want a laser that sweeps from side to side rather than "lol Itano Circus?"
So here are a few semi-tested upgrades, and then later there will be some highly experimental ones which may well be utterly broken. Remember, all weapon upgrades can be "stacked," so you can certainly have an Arcing Area Infinite Burst weapon, but yes you do have to resolve every single one of those individual lightning bolts individually.
Arcing: x3.67 Cost
Arcing weapons function a little like Area weapons, but instead of blanketing an area with beams they fire a lightning bolt or bouncing beam which jumps from target to target. When an Arcing weapon is fired, designate the Primary target and roll To Hit as normal. Then, pick one target within half the weapon's Combat Range. The player must roll to evade or take damage from the weapon. Repeat, halving the weapon's range each "bounce" until there are no valid targets or the weapon's range is reduced to less than 1 hex.
Piercing: x1.75 Cost
Piercing weapons are a step down from Area: Hex weapons. Trace a straight line one hex in size from the firing unit to the weapon's Combat Range. All targets on that line are hit.
Sweeping: x2 (60) / x5 (180) / x6 (270) / x8 (360) Cost
Sweeping weapons are slow-moving beams which are traversed from target to target, either by a tall turret mount or by the mech itself turning to face the target. In game terms, they count as appropriately designed Area weapons, with certain changes. The player must declare at what range the Sweeping weapon is being fired, and only targets at that range or one hex nearer may be hit normally. If something blocks the beam, it is hit instead and any targets obscured by it are unaffected.
Example for Sweeping: The Monkeylord is a heavy Cybran Mekton with a Microwave Laser, a 270 Degree Sweeping Weapon. Its player declares it is firing the beam at range 11, and begins the sweep. Any targets 10 or 11 hexes away would normally be hit. However, the UEF commander who is 10 hexes away is standing behind a Titan Siege Bot, which is only 6 hexes away. The Titan is hit by the beam and the Commander is unaffected.
All Sweeping, Arcing and Piercing weapons may only be fired at Combat Range, and may not take the Long Range upgrade.
Anti-Air: x1.25 Cost, may be combined with Long Range at a total Cost of x1.67
Anti-Air weapons are specially designed to be fired upwards, either through sophisticated Lead Indicators, rocket-assisted munitions or other tricks. They suffer no range penalties for Altitude when firing at Flying targets.
Fast-Tracking: x2 Cost (Ballistic/Energy), may be combined with Anti-Air and Long Range.
Fast-Tracking weapons use sophisticated actuators and hydraulics alongside advanced targeting computers (or artificial muscles, or whatever your setting uses) to compensate for fast-moving targets. They suffer no penalty for firing at targets which have moved more than 8 hexes in one turn.
Those are the tested weapons. They should be balanced, and as a DM I'd let my players use them for sure. A long-range Arcing beam might hit a lot of targets, but it will also be big. Fast-Tracking and Anti-Air weapons with a high WA bonus and Tracer rounds will be just the ticket against annoying fighters that your mechs can't hit.
And now the untested ones. These should only be used at the DM's discretion - they can get very powerful. Especially when combined. Thermobaric D-EMP mines are just overkill, and make NO SENSE.
Plasma: x5 Cost on Projectile Weapons
The weapon is now counted as an Energy weapon. It no longer requires Ammo, and specialist ammunition becomes a Cost-only multiplier. All resistances, reflector shields and anti-beam armours count against attacks from a Plasma weapon.
The following ammo types are compatible:
Mercury Ammunition: x5 Ammunition Cost
Thermobaric: x10 Missile Cost
Cluster Mine: x2.5 Ammunition/Missile Cost
Cluster Mine ammunition does no direct damage, and must have a Blast Radius. Instead, mark all hexes within the radius. Anything which moves into or out of a marked hex counts as hit by a 0-Range missile attack or salvo. A hex can be marked multiple times, and for each mark a victim takes one hit. Once the hits are resolved, the hex is no longer marked. Ordinarily, infantry or pilots out of their mechs will not trigger the large anti-tank mines, but at the Referee's discretion anti-personnel minefields may be laid.
Flying units, or units using Gravitic Propulsion, will not detonate mines. Mines cannot be normally laid in space or water hexes.
To finish, I'll offer some general "house rules" which can make your games more fun: