1. Alchemy, the ability to create potions that do cool things, such as make you bigger or smaller, make you faster, pale death, and things like that, but potions should be super costly to make and take actual hours to brew.
2. Cooking, as fish already heal you, cooking should make the food heal for more, and actual animals could be added, like pigs or cows or things of that subject that you can kill to get food, you can make stew, pork chops, etc. This should also take time to do, as this could be a very powerful new aspect
3. Foraging, with Alchemy and Cooking there should be foraging, killing Goblins and Spiders to get ingredients for potions, etc: Goblin Tongue, Spider Leg. Or even foraging plants, like requiring certain spices to make food, such as chives or whatever.
4. Skills, doing things such as fishing more, mining more, killing more, you slowly upgrade those skills making you better at them and increasing the odds of you getting better drops.

yeah and to not make the potions too op, they should last for a few hours or something