In D:OS1 Madora use only the sword, my both bows and only Jahan some healing spells and telekinese.
Same in D:OS2 2 Bowman, 1 tank and one healer (I always use easyest mode)
Seams BG need more than only weapons.
My advice is don't play BG3 as you play DOS1 and 2 because they are completely and vastly different in terms of combat.
You need to pay attention to:
- The positioning of your party and the enemy NPCs.
- The order in which NPCs are coming up in next turns.
- Dispatching enemies with smaller HP before focusing on those with bigger HP.
- Gaining advantage on enemies.
- Increasing your chance to hit enemies.
- Knowing when and when not to crowd control enemies.
Weapons and armors are helpful, but not in such a way that it would negate badly played turns. And even if you are geared with best gear in the game, bad decisions can still wipe you out.