First of all you're correct. The first day of unleavened bread is never technically called a "sabbath" in Leviticus 23. It is, as you've pointed out, a commanded day of worship and a day of no servile work. However, other holy days (atonement, trumpets) are specifically called sabbaths. By nt times (apparently) the other feast days have come to be called annual sabbaths, or high sabbaths, to distinguish them from the weekly sabbaths.
Joh 19:14 And it was the preparation of the passover, and about the sixth hour: and he saith unto the Jews, Behold your King!
Joh 19:31 The Jews therefore, because it was the preparation, that the bodies should not remain upon the cross on the sabbath day, (for that sabbath day was a high day,) besought Pilate that their legs might be broken, and that they might be taken away.
But I'm not sure what the point is in drawing the distinction?
And even if it were, that would only make it more unbelievable that an event which happened on a Saturday AFTER such a Sabbath would be said to have happened “on the first of the Sabbaths.”
As Diego pointed out (I believe) "first of the sabbaths" refers to the count of 7 sabbaths (or 7 weeks of sabbaths) used to determine Pentecost. To be fair, those who observe God's holy days DO have a difference of opinion on when to start this count and thus disagree on when to observe Pentecost. But THAT'S a thread all by itself. :-)
>> As Diego pointed out (I believe) “first of the sabbaths” refers to the count of 7 sabbaths (or 7 weeks of sabbaths) used to determine Pentecost. <<
And I was asking for evidence of this assertion. I’ve gotten none
>> But I’m not sure what the point is in drawing the distinction? <<
Because, otherwise, the “day before the Sabbath” means Friday. And “after the Sabbath had passed” means Sunday.
>> By nt times (apparently) the other feast days have come to be called annual sabbaths, or high sabbaths, to distinguish them from the weekly sabbaths. <<
So says you. Where’s the support?