The act of healing directly in combat (such as getting kevlar while fighting inside a gang HQ or taking food while you are being shot at) is against the rules as it constitutes script abuse, which since the beginning of Argonath has been a bannable offense.
Healing should only be allowed provided the combatant exits the area of fire (as it is technically no longer healing in combat), such as running for cover so a medic can do the job. Otherwise, any attempts to heal in combat should be punished by admins.
This is based on Argonath rules.