Just to clarify--is it <Weapon Unleash> that doesn't work, or does <Replace Attack: x> also not register on an off-hand weapon? If it's the former, no big deal--but if it's the latter, that's a serious bummer as it would stop me from doing things like having daggers key off of attack + agility, etc.
Unfortunately, it's both, as that plugin was never designed with dual wielding in mind.
The issue stems from the way dual wielding works by default in engine. The weapon unleash plugin only expects one attack, (as in the default implementation, dual wielding is still only one attack), and therefore only uses the weapon unleash (or replace attack) from the first weapon.
My plugin works by making the default attack action strike twice, which causes the weapon unleash or replace attacks from the unleash plugin to happen twice, not take one from each weapon.
This is something that could be fixed in an update, but wasn't on my roadmap until just now, and it involves deep diving into another plugin to make it compatible, so I wouldn't expect it anytime soon.
Bummer! I'd been pretty jazzed about differentiating weapon attack formulas as one of the perks of weapon unleash (honestly more than actual unleash skills!) since I could diversify the arsenal / make gearing a little more nuanced than just 'Stack as much atk as possible!'--so I presently have some weapons that use different combinations / ratios of attack, agility, defense, etc. for their default attack replacements. I'd certainly appreciate any endeavor to back-port a support hook for the plugin, but understand if it isn't a priority. Thanks for your time and attention just the same and kudos again for some really fantastic plugins!
One quick aside as a possible stop-gap, at least--even if I end up having to give up on the different formula for now. Might there be some way to partially restrict which kinds of offhand equips could be made based on the main hand?
Whether that's going 'pair daggers together' or fist weapons or whatnot, but also if there's something like a hand crossbow it's weird to go hand crossbow + melee weapon and have the character stand back and stab from the back line after taking a primary ranged shot.
One of the things I was using there replacement attacks for was for action sequencing + animations in general, so that I could ensure that if someone was using a spear they'd thrust, etc.; I'm likely overcomplicating this though!
I don't think locking certain weapontypes from being used together while dual wielding is currently possible, although you might be able to rig something up with Yanfly's equip requirements plugin to prevent certain weapons from being equipped entirely if another weapontype is already equipped.
That is actually a good suggestion though, so I'll see what I can do about adding support for that into the plugin.
On another note, you can use if conditions in action sequences to do different things when different weapons are equipped on the same skill. I personally have my attack sequence check the actor's weapon motion type to see if he's using a ranged weapon to decide if he runs into melee range, or steps forward for a ranged attack. The <Target Action> section of your action sequence on your attack skills will be repeated twice, once for each weapon, so an if condition that checks what motion is being used in that section will update when the weapons are swapped. You can use this to have a sequence where if the actor was using a crossbow in his main hand, and a sword in his offhand, the actor would shoot from ranged and then run in for his second melee attack, and even the reverse, although personally I think it looks better to swing in melee and then point blank shoot a crossbow into melee as well, but what do I know? :)