What’s happening is that Tolkien is using flaming as a participle not as a gerund. It is not acting as a noun, but as a modifier. It’s like saying “The widow weeping in despair collapsed into my arms.”
Tolkien does this from time to time in his other poetry as well. For example, from the
song of Eärendil which Bilbo cheekily recounts in (Eärendil’s son) Elrond’s halls from The Lord of the Rings:
There flying Elwing came to him,
and flame was in the darkness lit;
more bright than light of diamond
the fire upon her carcanet.
A lesser known instance occurs in the alliterative poem that begat The Children of Húrin from The Lays of Beleriand:
For Turgon towering in terrible anger
a pathway clove him with his pale sword-blade
out of that slaughter — yea, his swath was plain
through the hosts of Hell like hay that lieth
all low on the lea where the long scythe goes.
For the record, the pale sword that the king wields is nothing less than Glamdring, which Gandalf would also wield thousands of years later.
And here it is again from the “Lay of Leithian”:
There Thingol sat and heard no sound
save far off footsteps on the ground;
no flute, no voice, no song of bird,
no choirs of windy leaves there stirred;
and Dairon coming no word spoke,
silent amid the woodland folk.
And then again later:
‘Death!’ echoed Dairon fierce and low,
but Lúthien trembling gasped in woe.
‘And death,’ said Thingol, ‘thou shouldst taste,
had I not sworn an oath in haste
Here are some citations from Tolkien doing the same thing in prose rather than in verse:
- And Oromë looking upon the Elves was filled with wonder, as though they were beings sudden and marvellous and unforeseen; for so it shall ever be with the Valar.
- But as the host of Fingolfin marched into Mithrim the Sun rose flaming in the West; and Fingolfin unfurled his blue and silver banners, and blew his horns, and flowers sprang beneath his marching feet, and the ages of the stars were ended.
- And Felagund seeing that he was forsaken took from his head the silver crown of Nargothrond and cast it at his feet, saying: ‘Your oaths of faith to me you may break, but I must hold my bond.
- Then Celegorm turned his horse, and spurred it upon Beren, purposing to ride him down; but Curufin swerving stooped and lifted Lúthien to his saddle, for he was a strong and cunning horseman.
- Then Beren lifting Curufin flung him from him, and bade him walk now back to his noble kinsfolk, who might teach him to turn his valour to worthier use.
- Huan leaping caught it in his mouth; but Curufin shot again, and Beren sprang before Lúthien, and the dart smote him in the breast.
- Then Saeros fleeing in terror before him fell into the chasm of a stream, and his body was broken on a great rock in the water.
- But Túrin entering stood beside Mîm, and offered him aid.
- Now Túrin coming down from Ered Wethrin sought for Finduilas in vain, roaming the woods beneath the mountains, wild and wary as a beast; and he waylaid all the roads that went north to the Pass of Sirion.
- But in that coffer lay the Necklace of the Dwarves, wherein was set the Silmaril; and Dior looking upon it knew it for a sign that Beren Erchamion and Lúthien Tinúviel had died indeed, and gone where go the race of Men to a fate beyond the world.
- But the eagles coming stooped upon the Orcs, and drove them shrieking back; and all were slain or cast into the deeps, so that rumour of the escape from Gondolin came not until long after to Morgoth’s ears.
- But when that ship returning at last out of the deep ocean foundered in the great storm within sight of the coasts of Middle-earth, Ulmo took him up, alone of all its mariners, and cast him onto the land near Vinyamar; and learning of the command laid upon Tuor by the Lord of Waters Voronwë was filled with wonder, and did not refuse him his guidance to the hidden door of Gondolin.
- And at times, when Eärendil returning drewnear again to Arda, she would fly to meet him, even as she had flown long ago, when she was rescued from the sea.
- And Sauron, sitting in his black seat in the midst of the Temple, had laughed when he heard the trumpets of Ar-Pharazôn sounding for battle; and again he had laughed when he heard the thunder of the storm; and a third time, even as he laughed at his own thought, thinking what he would do now in the world, being rid of the Edain for ever, he was taken in the midst of his mirth, and his seat and his temple fell into the abyss.
- Bilbo seeing what had happened and having nothing better to ask stuck to his question.
- Gandalf whistled and called aloud the horse’s name, and far away he tossed his head and neighed, and turning sped towards the host like an arrow.
- Frodo coming behind grabbed his leg and threw him.
- Sam, supporting and guiding his stumbling master, followed after him as quickly as he could.
- Gollum misunderstanding the gesture, squealed and fell down.
- Sea-crafty men of the Ethir gazing southward spoke of a change coming with a fresh wind from the Sea.
- Before his upraised hand the foul Messenger recoiled, and Gandalf coming seized and took from him the tokens: coat, cloak, and sword.
- And Gandalf coming looked at it, and said: ‘Verily this is a sapling of the line of Nimloth the fair; and that was a seedling of Galathilion, and that a fruit of Telperion of many names, Eldest of Trees.