2 Legendaries equipped
Legendary in your main hand takes priority.
Footsteps will always be whats in your main-hand.
If the legendary in your off-hand has an aura effect however, it will stack untop of the mainhand legendary if it also has an aura.
Example: Frostfang and Bolt – Ice Footprints and and Ice arm, with a Lightning Aura.
I got both of them. Footprints are from frostfang, fog aura from howler and ice arm from frostfang, you also still get animation weapon change from howler . I think this two match perfectly with each other. Only thing you don’t get is obviously footprints from howler because you have them from frostfang.