Does the symbol on the Gjallarhorn have any significance (the two headed bird)?
The only other instances of a similar bird in game I think are Crucible and Zavala, but not only are those 2 different birds (Crucible is splayed wings with swords and a circle in the center, Zavala is smooth wings with legs out), neither of them seem to match Gjally which has no wings at all.
Even if they were the same, Gjally was forged of the armor of the fallen, which Shaxx and Zavala are not. Is it the symbol of a forgotten titan order?