Hi Sialia, I got referenced here from your post in the EN World name and avatar thread in Off-Topic. The long story of my user name can be found in that thread, but essentially, Firelance is the name of an NPC hero in a long-abandoned homebrew world who best embodied the philosophy of fire. He was formerly human, but became infused with the essence of fire and evolved into a phoenix. The Fire Lance was also the name of his weapon, which in 3e terms would be a holy, flaming lance (more a longspear than a jousting lance).
I realise that this is skirting the issue of character portraits, but if the concept strikes your fancy, would you consider doing an avatar of a holy, flaming lance or a phoenix wielding a holy, flaming lance? An avatar of a phoenix by itself has probably been done to death.