In Arcuz 2, there is a new partner (archer), Kimura who will help you throughout the perilous journeys in the Dungeons. Kimura is quite helpful as he can 'distract' enemies' attention, or help you avoid some critical attacks from the bosses/creeps.
So, it would be great if you can heal Kimura from time to time using the potions or magics. But, unfortunately, in the battlefields/Dungeons, it seems that you are unable to heal Kimura using the healing potions as you use to yourself. You can only heal him through the conversation with the Celest in the village.