They both leave you close to death considering with firebolt/Viking funeral regardless of when you take additional damage you'll burn out all the same. The difference is any other grenade will leave you one shot. But then depending on your recovery stat you can start to heal and get back in the fight. With Viking funeral/firebolt it takes about 9-12 seconds depending on recovery stat to not be one shot and then another second or so before fully healed. That many seconds in game is an eternity