Maxperson
Morkus from Orkus
If it were not made only of fire, it would do damage other than fire. A Flame Tongue doesn't just do 2d6 fire damage. At best only the hilt is solid.The blade is a fiery blade, it doesn't say it's literally only made of fire. But we know SOMETHING is in your hand. It's not VFX - you hold the blade, and if you open your hand the blade goes away. Something is physically there to hold. For my game, that's an object.
Edit: Ice Storm does physical and cold damage. Meteor Swarm does physical and fire damage. If a damage dealing spell is both physical and energy, both deal damage.