Since the weapon draw and sheath animations have been added to the game, I’ve noticed an oversight when using any one-handed weapon type and a shield. The weapon animation always cancels out the shields animation when pressing the equip weapon button, both for draw and sheath.
This effectively makes the shield teleport from your back to your hand an vice-versa.
In the GIF above, you can see that when equipped separately, my character pulls both the shield and sword from his back, physically grabbing them both in the animations.
In this GIF, you can see that when I use the draw/sheath button (hold Y in my case) my character pulls the sword from his back but the shield jumps immediately from his back to his hand.