The correct sequence is implied by the two previous sequences. In the chamber containing Ahzidal's Armor of Retribution there is a dual-function rune totem puzzle.
The first sequence, required to open the portcullis to allow you to retrieve the armour, is found by:
Pulling the chains on each side of the chamber to activate a spinning doorway that reveals the correct runes - which happen to both be the same rune (which we'll call Rune 1).
The second sequence, required to open both the door that locks behind you once you enter the chamber and the grate in the floor, allowing access to the level below and the third totem puzzle:
Is in plain sight. The two required runes are shown on the wall opposite the totems and the lever. Again, the correct sequence is two of the same rune (which we'll call Rune 2).
Given that each rune totem only has three different runes available, and the pattern that the previous rune puzzles followed, the third sequence required to retrieve Ahzidal's Helm of Vision must be:
Both rune totems set to the same symbol, Rune 3.
So, to be more specific, explicitly naming the runes in each sequence:
The first sequence, allowing the retrieval of the Armor is Whale, Whale.
The second sequence, opening the grate and allowing you to continue is Eagle, Eagle.
The third and final sequence is therefore Snake, Snake