There seems to be a bug with the healing and mana potions. The higher tier potions give less health points than the lower tier ones (I have attached the potions and there values below)
Minor Healing Potion heals for 88 health
Lesser Healing Potion (req lvl 2): 122 health
Healing Potion: 75 health (heals less than lesser healing?)
Greater Healing Potion: 75 healing req lvl 10.
Superior Healing Potion: 114
This also applies for the mana potions as well (lesser mana potion- restores 190 mana but the higher tear regular mana potions only restore 120)