Abyssal Armoury

You channel abyssal power through your arm into a melee weapon you are holding.  The arm and the weapon are covered in swirling red flames, shedding bright light in a ten foot radius and dim light for another 10 feet.  Each successful hit with the weapon deals an additional 1D8 fire damage and you can make a single attack as a Bonus Action.  You can make a single attack as part of the casting of this spell.