Just remember that the 5% attack passive affects Artemis only. As I have explained already in my previous posts, most of Bryn's skills affects the whole party. The balance of your party is important, and until you reach enough power/hp where you can survive longer than the enemy, healers are essential. That said, you can always change your Heroic Spirit into a healer, but then you give up a lot of versatility for that. With some content, it may even be beneficial to have multiple healers.
Another way around it is to use potions to heal your party, but that costs limited resources. Once you exhaust your resources, you'll either have to waste AP to farm more or purchase with real money. And during certain events, AP is a limited resource in itself so it'll be difficult to say the least.