Currently there are no STR/DEX shields, so if you want to block with a Shield and use STR/DEX weapon, you have to have been a packrat leveling so you have a shield for which you meet the stat requirements.
Suggestion: Add a STR/DEX shield in each class of shield.
Attributes are going away with the class system, and I doubt devs will create weapons or change anything about attributes until then.
Also, shields do not actually scale with stats very much, so just craft one with a low-level char and upgrade it. Won’t raise attribute requirements.