Here is an explanation of Seshat's names and titles, including Sefkhet-Abwy:

[seshat.org]

The supposed bow or inverted horns above the seven pointed symbol looks to me like the sun disk symbol with a nipple in the middle, from a side on perspective. If so, then maybe the seven pointed symbol is occulted by the sun disk in it's normal front on presentation.

In the pyramid texts Seshat appears to be identified with Nephthys:

"Nephthys has collected all your members for you in this her name of 'Seshat, Lady of Builders'." (Faulkner - section 616)