Ritva: "Surely the Eyptians didn't see the stars as sharp, but shining. Now, it seems that either they had only one word designing the words sharp and shining (which Sirius undoubtedly is), or the two determinatives are not the same. Needless to say, that the form of a pyramid fits wonderfully in the context of "shining" and much less in the idea of it being a thorn."
Not so much as "being a thorn", but sharp. A pyramid is 'sharp' in the sense that its a pointed building with a 'sharp' pointed top. Names of pyramids were in a few cases explicitly stellar or had stellar associations.
AE stars were usually 5-pointed - 5 'sharp' triangles, often drawn around a circle in the centre.
Perhaps the idea of 'sharp' in the context of a star, has something to do with the appearance of a very bright star like Sirius or a bright planet that can appear like sparkling gems in the sky - 'spiky' / 'sharp' - especially if its cold night and the eyes are moist.
A word-play on spdt from PT 366. Allen's translation: "Your sister Isis has come to you, aroused [for] love of you. You have put her on your phallus so that your seed might emerge into her, sharp (spdt) as Sothis (spdt), and sharp (spdt) Horus has emerged from you as Horus in Sothis (spdt)" (Sethe Vol 1: 342; §632)
spdt is written here: S29 (s) M 44 Q3 (p) D46 (d) X1 (t) Sopdet (Sothis) has the additional 'star' determinative, N14.
Sopdet (spdt) can also be written simply with the 'triangle' M44 and X1 (t) + 'star' det. N14.
spd could have an underlying meaning of effective, alert.
The name of Djedefra's pyramid was sHdw - Dd=f ra, variously translated as 'Djedefra is a shining star' (Strudwick), 'Djedefre is a sehed-star' (Edwards) etc., so at least from Strudwick's translation, the idea of shining / star / pyramid is apparent.
sHd can have the meaning of illumine / shine, and with the star det. N14, is also a kind of star - invariably associated with the sun. sHd-star in the Pyramid Texts:
"this Pepi will row the Sun in the sky's span, a star of gold (sHd n nb) on whom the sunlight's bull has put the headband, a spear to the sky's span. (Sethe Vol 1: 496; §889d)
"Teti's star (sHd) has been elevated (sqA) with the Sun." (Sethe Vol 1: 379; §698b)
"Pepi is a star (sH(d)" (Sethe Vol 2: 304; §1470b)
Faulkner gives an example of an epithet of the sun, 'Great Light Maker' (sHd wr), but it has the star det. N14. (Faulkner 2002 (1962): 239) - one might suspect the AE thought the sun (ra) was the brightest star in their sky.
CT