Two things. Graphic and the game numbers.
The in-game graphic for block angle is off on shield and spear. The shield and spear shows 150 degrees, despite being a 120 degree weapon:
The main issue is what the actual in-game value is versus what the graphic shows. The armory mod says that the elf shield is actually 120 degrees, not 180(or even 150). The elf shield has less block angle than the spear. The spear has 180 degrees versus shield+spear having 120.
In fact, even Kruber’s 2 shields are different. The Sword and Shield has 120 degrees while the Mace and Shield has 180. Bardin’s shields are both 180.
While I don’t know if you’d call what appears to be human error a bug, it’s still definitely an issue but should be an easy fix(the in-game numbers anyways).