Thanks for the input, and when you're breaking it down like that, it does seem like a lot is going on. And thinking even harder, it does get pretty complicated, especially with the amount of skills there are. Later on, you need to have really well designed classes to take on enemies.
The boost is there for really your big damage after you break the shields of an enemy. But I suppose it's all the same in the end, it just adds some variability. But there are so really cool things I think too, like for example: Sorry for wall of text:
Having a rogue in your group, you can use an ability that when used on an enemy, the overkill damage is stored for the next attack. So in theory, you can use it to kill an enemy and store that damage. Then the next turn you have an ability that grants your next attack an automatic crit. So on that turn you timed it to break the big enemies shield before you rogue's turn, then your rogue uses their relic power to triple their damage, which now consists of the overkill damage as well as being an automatic crit, then you have the bard cast their ultimate spell on the rogue which replicates their next attack. So this huge combo does a metric fuckton of damage.
But thinking about doing stuff that complicated, maybe it would get hard to balance, because then I'd have to balance for those really big attacks?
As for downsizing, which would you think would be a better way to go about it? Losing the relic damage boost system, or losing the shield break system? (The weapon swap needs to stay because of stats for hybrid characters, and some abilities require certain weapons. When you can choose any classes' abilities, being able to equip 2 weapons gives you more of a wide variety of abilities you could use at least.)
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I definetly think the weapon swap should stay aswell, I haven't used it in the Demo a lot, but its a very uncomplicated system that can easily change combat up a bit and it feels fairly unique for a JRPG.
I think your best bet would probably be to see which you can make more interesting. using relics to properly alter/improve your skills instead of just numbers going up, or more uniqueness in the shieldbreak system? Not every enemy having it, skills giving/taking shield points, only particular weapons affecting it (this ones already in if I recall correctly). If you get both to synergize well with each other, instead of feeling so much like 2 different systems you could potentially keep both aswell.
Personally I'd probably go with the shield break. If you expand that as mentioned above, it can work quite well also with the weapon swapping, since you can only break shields with certain weapons/weaponskills, maybe forcing you into your secondary weapon if you want to break that specific shield to be able to use a spell which would otherwise just be ignored or something.
*Edit: Be sure to play and test around with your current setup first tho. It'd be a shame if my stupid Ideas ruined your Combat.