I think it means to "flail" Flailing is mainly used to describe the movement of arms of legs when they are moving in quick way with little control. So basically they are flopping their arms around

This is the dictionary definition of this word: flare fler/ noun 1. a sudden brief burst of bright flame or light. "the flare of the match lit up his face" synonyms: blaze, flash, dazzle, burst, flicker "the flare of the match" 2. a gradual widening, especially of a skirt or pants. "as you knit, add a flare or curve a hem" verb 1. burn with a sudden intensity. "the blaze across the water flared" synonyms: blaze, flash, flare up, flame, burn; More 2. gradually become wider at one end. "a flared skirt" But in some examples I saw it used in a simular fashion to "flail" In the example you gave I like to imagine it like how fire moves. its rapid random movements with a snap to them. I hope this helps, Jack Lindsay