I never noticed the 120 push/block angle on the sword/shield. But I do believe that the sword/shield is the worst out of the 3 shield weapons, by far - that would definitely be part of the cause though I’m sure.
First off, let’s look at the niche the sword/shield fills (maybe someone who uses it more can correct me here if I’m wrong). It seems to be a crowd killing/crowd control hybrid - being able to knock enemies around, and kill them in the process. It’s actually a fairly unique weapon in this regard. The only problem is that you don’t really need both at the same time, and since it’s a weapon balanced around having both they are both sub-par.
The mace/shield is pure crowd control, one of the best weapons for that in the game imo. Axe/shield is hybrid between crowd control and dueling.
My suggestion would be to pick either the crowd control or the crowd killing aspect of the sword/shield and build upon it. Maybe increase the push/block angle and give more cleave or stagger to the sword attacks for CC, or increase damage but reduce cleave damage for CK.