That's just French for "masterful" or a way to describe lectures. There's a sense of greatness in that word that contrasts with the Mini in Ministral which is in turn might be a pun on "ménestrel" (minstrel), "ministre" (minister), or made to sound like Minitel (or all of the above).
Allow me to contribute:
> Magistral: Magist(rate) + stral? Mag(nificent) + stral? Nobody knows.
That's just French for "masterful" or a way to describe lectures. There's a sense of greatness in that word that contrasts with the Mini in Ministral which is in turn might be a pun on "ménestrel" (minstrel), "ministre" (minister), or made to sound like Minitel (or all of the above).