It’s an Olllld English word, first meaning “a torch” and then the fire on the torch, related to many Germanic words bound together by the sense of “shiny”. I am tempted to try “blazin'” as my new enthusiasm-communicating word.
“blaze, n.1.” OED Online, Oxford University Press, June 2020, http://www.oed.com/view/Entry/20003. Accessed 10 July 2020.
See how sparingly JRRT uses it! See how it anchors the very pivot point of the book!
[17.041] ‘Halt!’ cried Gandalf, who appeared suddenly, and stood alone, with arms uplifted, between the advancing dwarves and the ranks awaiting them. ‘Halt!’ he called in a voice like thunder, and his staff blazed forth with a flash like the lightning. ‘Dread has come upon you all! Alas! it has come more swiftly than I guessed. The Goblins are upon you! Bolg of the North is coming, O Dain! whose father you slew in Moria. Behold! the bats are above his army like a sea of locusts. They ride upon wolves and Wargs are in their train!’
• 1.079 The trees like torches blazed with light.
• 6.058 with eyes blazing
• 6.078 till beards blaze, and eyes glaze;
• 7.084 and the forest beginning to blaze
• 8.063 he stumbled forward into the full blaze of the fire
• 8.070 There’s a regular blaze of light
• 12.022 and up he soared blazing into the air
• 12.027 at any moment he might come blazing down
• 14.013 the dragon’s wrath blazed to its height,
• 17.041 and his staff blazed forth