Your Myriad lets you have 2 Actions?

I fully committed to giving characters  2 actions in order to answer a question as old as time itself:  How does dual wielding work?

Seriously.

I've thought a lot about that and never have had a great answer. On one hand, dual wielding somehow always ends up being a bad option in tabletop games that force you to take feats to cover up the strict penalties for doing it. On the other hand, if all of that wasn't there it would be extremely powerful to the point it overshadows everything else. Adding additional attacks is a big deal. In original Pathfinder, one of the most powerful thing martial classes can do is gain extra arms to attack multiple times and carry flat bonuses to each strike. A sneak-attacking wild-shaped Octopus with 8 arms is pretty good.

The trick here with the 2 Action setup I've implemented is that you can NOT take the same action twice during a turn. This includes using the same weapon twice, which it will track and prevent. You also can not use an action with anything that did not start its turn in your hands, to prevent constantly quick-swapping items to use the exact right combination of actions. You have to actually be holding 2 weapons in order to gain the benefit of dual wielding.

Some weapons, like Rapiers, have been given the 'Relentless' tag to be able to use any number of actions with the same weapon. 'Heavy' weapons require 2 Actions to attack instead of 1 and some powerful spells also use 2 actions. Some randomly generated items can require +1 Action to use...and even +1 hand! You could find a super large rapier that needs 3 actions and 3 hands to wield. That example is very uncommon, but definitely possible within the randomly generated item system.

Ultimately, I feel this diversifies player turns and actions more than anything else could. Wielding a mace and shield suddenly feels more like a hybrid spellcaster due to the extra action you have left over after making an attack with the 1 handed mace. Shields have also had a more functional chance to block and % of damage reduction that can be scaled, rather than the slight defense increase they would offer before. All of this is added on top of the sweeping changes to weapons that have been made to allow a really distinct feel to characters simply based on what equipment types they are using.

Dexterity skill options supplement these changes to have ways to quickly change weapons, action surge, and refresh which actions you have used during your turn so that they may be used again. Daggers also attack twice for every 1 action used to attack with a single dagger. Dual wielding daggers nets you 4 attacks against an enemy, which may be powerfully boosted with a ton of accuracy you've cultivated through free action adrenaline spenders. Each hit can also carry status effects like poison or bleed. Dual wielding is a distinctly powerful option that stands on its own with all of these changes in mind, but other choices also got equally more interesting as a result.

As an extra note, 'Start of Turn' actions still exist as well. I was unsure if having 2 actions would make them irrelevant, but that hasn't seemed to be the case. One great example of how they still work within this system is a skill called 'Quick Swap'. At the start of your turn you may spend Adrenaline in order to change your equipped items so that you may immediately use actions with them. 'Start of Turn' actions are generally quick bonuses that are restricted by resource pool use or are very short range so the planning and positioning of where you will start your next turn can be taken fully into consideration.