Trying to find fantasy novel from friend's childhood (late 80's)

I'm trying to help my friend find a book. The following is all he remembers about it from his childhood. He's in his mid-late twenties.

The main character is a girl / young woman. The city she lives in is facing an impending attack. She and her father are chosen (or might already be, can't remember) as sacred, magical warriors to defend the city. Their power is that they can see through one another's eyes and fight like a sort of four-armed berserker with 360 degree vision. I think the name for them begins with an S.

The invasion comes, they fight, her father is killed, and the bad guys win. She becomes involved with a rebellion, and at the very end of the book they are successful in overthrowing the bad guys. The main villain is a traitor, I believe. The king's advisor, or something like that.

I think the first battle takes place on a beach, maybe.

I vaugely recall that book, can't think of the title right now but will come back if I recall it. Did they wear kilts or something similar when they fought?

Could be The Sword and the Lion by Ru Emerson writing as Roberta Cray.

Cray, Roberta: THE SWORD AND THE LION - Out-of-print, for readers who like thick books; a Trojan-War-like story of father-daughter fighter teams used by the gods of the city, an exploration of soldiers living among civilians, effects of long-term sieges, a peacetime king faced with a conquering enemy who possesses alien magic, political maneuvering in wartime

Ru Emerson published this fantasy under the pen name Roberta Cray. Lengthy stand-alone story taking place in an area reminiscent of the ancient Middle East (Babylon, Sumeria - you know, deserts and lion gods, and dusty walled cities baking under the hot sun). Lots of battles and a young heroine who grows into a great destiny.

Edit to fix the touchstone

Sounds like the one I was thinking of

I will definitely find out if this is it. Thank you so much for following up!

You guys ROCK!!!!! That was indeed the book. He'd been looking for it for many years. Thanks so much for your replies!

I'm glad we found it for you. Thanks for coming back and confirming the find. Hope he enjoys it as much the second time around. : )