Exastrapto describes a flashing appearance, used of the clothing becoming white during prayer.

The attested use describes a flashing quality in the scene where the clothing becomes white while he is praying.

1. Flashing in a changed appearance · dominant

   In Luke 9:29, ἐξαστράπτων is a present active participle in the clause about clothing becoming white; the APB renders the clothing as "was flashing forth."

   Luke 9:29

In the Anselm Project Bible: In Luke 9:29, the APB presents the clause as clothing that "became white and was flashing forth." That wording confirms the scene's overall presentation rather than isolating every contribution of the term.