I encountered this word at an article and after googling I have come to know this word is Shakepear's play origin.
And I found this site., and I found another site, which was explaining that the 'd means the past form of the verb scepter, whose definition is below by Merriam.
or British scep·tre scep·tered or British scep·tred; sceptered or British sceptred; scep·ter·ing or British scep·tring; scep·ters or British scep·tres 1 : to endow with the scepter : invest with royal authority 2 : to ratify by touching with the scepter
So would this (probably) old word, scepter'd isle, be some kind of a noun prasing the royal family and their reign in Britain and consequently be the synonym of praise to the England?
Or ultimately saying, this word would mean the "island under ( (blessed) the U.K's royal family's sovereignty? " Kindly confirm. Thank you.