Dear Brothers and Sisters,
Again, I am sorry for such a delayed response to this post. I'm typically tardy most of the times! Did you figure out that under 'S' 'Lu' 'Se', it reads, 'Q' 'Du' 'S(e)': literally, 'Trinity Holy'.
Xiara, usually in the Holy Trinity icons that are written by Ehiopian iconographers, one can see that the beards on the three Persons are long [the Father], longer [the Son] and longest [the Paraklete]. Of course, this represents not age, but the 'functions' of the Persons. The Father is the Begetter and causes Procession, but is not begotten nor does He proceed. The Son is the only-Begotten, but does not cause procession nor does He beget or proceed. The Paraklete is not Begotten, does not beget, does not cause procession, but Proceeds only. This 'style' is fashioned to express the Persons as individuals, although they are one in Essence.
They are sitting on the 'meseret' of Menbere Mengist, which is just an icon of the Lord's Kingdom. It is not a literal 'glass throne' that sits on the 'sea' as most people think, due to the misinterpretation of St. John's words. Hence, the Cherubim [and the teaching of some traditional Ethiopian scholars who say that there are Seven Heavens] who bare that so-called 'transparent' throne and dwell in se'ma'y we'du'd [the Kingdom of God that rests on the back of the Cherubim].
I hope that this helps. Take care and peace to you...