Nelchael is listed in Heinrich Cornelius Agrippa’s Three Books of Occult Philosophy, Book III, chapter 25.
The seventy-two-name table
The chapter presents a table headed as seventy-two angels bearing the name of God, Schemhamphoras. Nelchael appears among its names in Joseph H. Peterson’s digital edition.
This gives the name a specific textual setting in Agrippa’s treatment of divine and angelic names.
Source
Agrippa, Occult Philosophy, III.25, seventy-two-name table, Peterson’s digital edition.