Glew is indeed a word, but it is not the past tense of glow. It is an archaic spelling of the word “glue.”
Sometimes people mistakenly think that glow follows the pattern of “throw,” “know,” or “grow” and forms its past tenses by changing the “-ow” to “-ew.” But these are irregular verbs and grow follows the regular verb pattern of adding “-ed.”
The flame glew in the distance and slowly faded.
The flame glowed in the distance and slowly faded.
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