Gregory Nagy has some interesting points to add about Pyrrhos the Wolf of Wilusa, whom Snorri presents as the personification of Surtr’s flame:
The description ‘fiery’ matches the hero’s name Púrrhos, deriving from the adjective purrhós, meaning ‘fiery red’, which in turn derives from the noun pûr ‘fire’. The description matches also the association of this hero with a kind of war dance known as the purrhíkhē—a word that likewise derives from the adjective purrhós. Here is a basic definition of the purrhíkhē as we find it in the ancient lexicographical tradition attributed to Hesychius (under the entry πυρριχίζειν): τήν ἐνόπλιον ὄρχησιν καὶ σύντονον πυρρίχην ἔλεγον ‘the word for energetic dancing in armor was purrhíkhē’. In the work that I am epitomizing, I offered detailed evidence to show that this kind of war dance was a ritual dramatization of biē ‘force, violence’ in warfare. I hold back on repeating the details here, except to add that the noun purrhíkhē is appropriate to the name Púrrhos, not only to the adjective purrhós, since there are myths that derive the name of the war dance from the name of the hero. According to the poetry of Archilochus (F 304W), for example, the word purrhíkhē refers to a war dance because Púrrhos danced such a war dance for joy after he killed the hero Eurypylos in the Trojan War. According to another tradition, mentioned by Lucian (On dance 9) and by other sources, Púrrhos not only “invented” the purrhíkhē: he also captured Troy through the ignition of this war dance, since he started the fire that burned down the city when he leapt out of the Wooden Horse, already dancing his dance and thus igniting the fire.