I feel that It should
1. Blow Hell alot Further with the fire since the fan would be Pushing the fire.
2. take 0-10 Fuel To Air-blast since THERE IS A FAN so either some where from 0-10 so maybe a random amount every time or just non and it would Airblast hella far.
3. The name AFTER BURN Should mean After you burn someone if you walk away it will last alot or a good amount longer then the normal fire on someone when they get hit.
And 4thly. it would take just a bit more fuel *maybe* to use the flame since it does have inf Airblast if it takes 0 to use and or just does a bit less dammage.
If you like my Ideas if valve adds it then Thanks. If you wana add your own comments go ahead.

Stamp of Approval.