Healing in Assassin’s Creed Odyssey is only going to be done in a couple of ways. The first is going to be the automatic healing that you receive when you are not in combat. The second is going to be the in-game healing that you can do when you purchase a special ability.
The automatic healing can only be done when you are not in combat. If you’ve taken too much damage, your best bet is to run away from the battle, hide until enemies can no longer see you and then regenerate your health.
The second way that you’ll unlock as you progress in the game is a healing ability that can be used during a fight. This is obviously a good ability to spend upgrade points on as it will help you stay alive for longer than running away every time you take damage.
The ability is called “Second Wind” and it’s in the Warrior sub-class of the ability trees. The first Second Wind ability will recover 25% of your max health and can be upgraded three times. To upgrade second wind to the maximum you will need to have Spear Level 5.