You Died Symbol Reference: Three Eyes Shield

You Died features a symbol of a shield with three vertically stacked eyes.

That symbol can also be found in Dark Souls: Design works on page 106. It didn’t, however, make it into the final game to the best of my knowledge.
The only instance of three vertically stacked eyes I could find in the game is the design of the Channeler enemy.

Channeler Concept Art in Dark Souls: Design Works

One idea Lokey brought up is that the Channeler was at one time supposed to be one of The Four Knights of Gwyn. And as a knight he might have had his own shield which might have been the Three Eyes Shield.

Mockup showing the Channeler with the Three Eyes Shield:

Here’s Miyazaki explaining their thought process in the interview found in Dark Souls: Design Works, page 120:

We decided to start calling them "The Four Knights", and named Smough and Channeler "Four Knights C" and "Four Knights D", respectively. You might be wondering why wen went straight for "C" and "D"... The reason was because we figured if we tagged the two we already had as "C" and "D", we'd naturally feel obligated to create "A" and "B". (laughts) Despite our clever plan, "A" and "B" were never created. Smough and Channeler became decidedly un-knightish and the whole "Four Knights" concept was only sort of carried on into the designs for characters like Ornstein and Artorias. Channeler couldn't be one of the Four Knights because he didn't end up being a one-of-a-kind character.

Miyazaki Interview Dark Souls: Design Works, p. 120

As we can see, FROMSOFTWARE ultimately went in another direction and the Channeler didn’t end up being a knight. But that unused shield design found in Dark Souls: Design Works might be a remnant of that earlier design phase.