You require two hands to use this weapon without a penalty.

[Otherlander]

This one has caused me to mull it over for a while, and I've come up with questions that I haven't been able to find the answers for. They are:
1) Consider this not-at-all hypothetical mecha: Has two arm mounts in addition to two hand mounts. Has a heavy flare cannon in his left hand, with nothing in his right hand, but has a beam bayonet on the right arm mount. The message always displays, as far as I can tell, so it doesn't seem to be telling me that I do indeed have this problem (Ie. I've gotten this message with no other gear equipped).
1a)What are the exact rules to this? Does have anything equipped in any of the other three slots reduce its efficacy? What about the collar mount?
1a-) Following a negative answer to the latter two, what of equipping it on the arm mount? Does equipping it to one arm mount mean the other must be clear? The other hand? Does the penalty cease to apply?
1b) And what if I equip it to the collar/torso mount? Does this no longer apply then?
2) And what exactly is the penalty, be it SF:0 or SF:2 that equips this? I can only assume a hit to accuracy or (in the case of melee weapons) damage, but that does not give me numbers.

Respectfully, thanks.

[Erathoniel]

I don't know the specifics, but I believe it's something like a -4 or so to hit (just taking a foggy guess here), it always occurs upon equipping a two-handed weapon, and if you equip it to the collar/torso mount you still get the penalty. In pretty much no order. Also, if you are using different arms or a DIY mecha, that might be the problem, though I get it myself on vanilla mecha all the time.

[Frumple]

Not really sure how it works either, but I can throw in a point or two. I've personally never noticed a problem s'long as I've got a hand open... or at least I always assumed that th'message popping up meant, yanno', keep a free hand, not 'penalty now, ahahahaha'. If there's an actual 'two-hand' flag, I don't think I've noticed it.

Anyway, the major factor to it keying in is mech size, as far as I've been able to tell. A larger machine (Not in tonnage, but in the design file, battroid 2 vs battroid 7; without opening those up to check, larger mecha have higher HP/armor/whateverthatnumberis ratings on their parts, and their limbs are usually heavier, barring mass reduction in the design.) can one-hand larger weapons.

The other thing is actuators, though I'm not sure if it's a cumulative effect across the machine or just in the limb it's installed in (In relation to the needing free hand thing, in other ways it's cumulative.). I've definitely had the message stop keying after installing an act or two, in any case.

So what keys the message is something in relation to the size of the mecha and the weight of the weapon, with actuators shifting the target zone around... somehow. I'd think keeping a hand free would prevent the penalty from coming into play, but would have to pull out the game and open up the roll history to actually find out... and I'm lazy, heh.

Anyway, hope that helps a little, until someone who's actually rummaged through the code comes and illuminates us all.

[Joseph Hewitt]

As long as you have one hand free, you can mount as many "You need two hands..." weapons as you like. That one empty hand will be very busy switching between all the weapons.

You can see whether or not the penalty applies by checking the roll history after making an attack; this modifier is listed as "weight". A mecha can lift (Size + 1) tons with one hand. A character can lift (Body / 2)kg with one hand.

[Erathoniel]

Ah, so that's how it works. I always wondered why my super-hacked characters never had problems dual-wielding plasma cannons and missile launchers.

[IronJelly]

* IronJelly gets a laugh out of the idea of dual wielded rocket launchers.

almost like dual chainsaws.