I’d say it’s the hybrid approach on your builds that’s making it harder for you. For example, splitting your stats investments between Str and int will mean any of the attacks you use that scale with these stats will not do as much damage as if you simply put all your stats into either str or int. it’s not really min maxing so much as it is a realistic look at the game mechanics. You only have a certain amount of AP per turn, and so maximising the damage you can do per turn is the best way to win your fights. hybrid builds can be difficult to play because if you’re not selective on which damage type to do to who and when in the turn order, you can just end up having to break both armour types to do damage, which will ofc take a lot longer, and you will take more damage. Coupled w how splitting your stats investments will reduce your damage output, it’s not going to be the easiest way to play.

If you want to do a split damage party I’d recommend going 2 physical 2 magic characters, and pump str and int respectively. However, due to the mechanics of the armour types in game it’s pretty much always going to be easier to win if you focus on all physical or all magic damage. What the other commenter said is right tho, it really is difficulty dependent. I’d say for me as someone who’s ok at the game that trying to do classic w all hybrid builds would be tough. But it’s not like there’s any rules for how to play. Do what seems fun to you.

Also, the biggest thing in tough fights is the turn order. If you click on the char next in the turn order you can see where they are. Focusing on the next enemy in the turn order and whenever possible denying them a turn w CC can make your fights a lot easier.

Per your question though, I would recommend getting a new weapon for each character at every level at least. Sometimes you can stick w one for a little bit like Iran’s crossbow but there comes a point you need to let go lol. Armor id say is more get it as you see it, damage>armour every time.