I'm running Mongoose Traveller and one of my players wants to have their PC dual-wield pistols. I can't find any rules for two-weapon fighting in the core book or Central Supply Catalog. The same question goes for two melee weapons, like swords and axes. How should I rule this?
The best way to rule two weapon fighting is treating it like "Multiple Actions" as stated on the p.50 of Core Rulebook. According this rule character will suffer -2 DM to all skill checks. Also it's good to increase recoil of the weapons by 1 as a result of trying to use each weapon in one hand and for the difficulty of keeping both guns on target.
And according for what I know about fighting with two swords this rules are applied well for them too.
The answer was written in accordance to this thread: http://forum.rpg.net/showthread.php?691317-Mongoose-Traveller-Rules-Questions
I'm tempted to suggest allowing them to fire a secondary weapon at the same target using their minor action, or maybe "charging" them a Reaction (-2 init, -1 skill checks until next round). Also, no aiming, since it's physically impossible to aim down both weapons without some electronic assistance.
As Kyle suggested, I'd do +1 Recoil. And maybe charge them for the Reaction BEFORE they fire, so they take the penalty then.
For melee weapons, I'd just allow the character to choose which weapon to attack with and which to parry with each round. Or charge them -1 for "dual weapons", but allow them to parry without the usual penalties. Which means that dual-wielders will be better at defending themselves, but not necessarily better on the attack.