There's a delay in Warband's blocking as well, it's fractional compared to Bannerlord but is just visible between a Pike and a Arming Sword for instance.
If delay is kept, perhaps its the values that need changing. I think currently the weight to delay is a consecutive value (i.e. 1 weight = 10 speed, 2 weight = 9 speed... 9 weight = 2 speed, 10 weight = 1 speed), or if not is a near consecutive value.
A more cumulative value starting higher and ending lower (i.e. 1 weight = 15 speed, 2 weight = 13.5 speed, 3 weight = 11.75 speed... 9 weight = 1.25 speed, 10 weight = 0.55 speed) could prove a better system.
This'll have a subtle nerf effect on weapons that are known to be rather powerful, such as the Menavlion or Glaive, making users work closer with their team mates and possibly have an actual use for the backup short sword many of the classes are given.
It'll also give infantry a subtle advantage against dismounted cavalry, as the longer, heavier cavalry swords will struggle to make blocks if their shield has been lost, encouraging less gung ho aggressiveness from mounted players with injured horses but also encouraging them to depend on teamplay when dismounted or injured.
Near nil blocking delay would be more competitive, but MnB is highly skilled based by its design. It's one of the reasons why people played so much, but also why others picked it up and dropped it shortly after. I can see why TW wanted to strike a balance between the two, but this balance is currently unsuitable for the majority of the experienced community. There are ways this system could work, but in this current form it is failing and needs addressing.