I absolutely love the idea of Directional blocking with shields. Perhaps change it a bit so that the shield will still block a swing from a different side, but make blocking in the correct direction somehow more effective- for example, the shield takes less damage. Intercepting a sword with the metal boss of the shield would take a much lesser toll then a blade hitting right on the edge.
Since Bannerlord is indeed focusing on a late roman/byzantine sort of period of warfare, the combat should reflect that. To the north the shield-wall was being developed, and in romanized lands the traditonal scutum and gladius were still a part of legionary doctrine even if the style of the equipment was changing. To reflect that, swords should have a more efficient stab than in warband. The floris mod pack includes something that accomplishes this nicely. Besides that, there absolutely should be a mechanic to allow people to stab and block at the same time as this was basic legionary doctrine. This would be a nice excuse to improve and expand upon shield-play in general.