Well, 4 shield skill sould be enough if you use a good shield with many hitpoints (especially needed is speed) like the Knightly Heater Shield. I played this shield with 4 shield skill one time and with 5-7 shield skill it's nearly unbreakable in normally melee and just if you DON'T fight against twohanded axe men. Hmm if you can't avoid a fight against an axe man, you could need your manual block skill
or just fight without shield if you think you need it after the fight:)
But all at all your build should be effective and one more thing is, if you use Normally - Heavy Armor
You would have an advantage if your shield breaks. Some players think they can hide behind their shield with light armor like Steppe Armor. Then if their shield breaks they will die immediately! So don't get such a light armor
Hope I can help ;)