So, I was able to make a Shield Defense/ Dual Blades tanker

[Major_Decoy]

And I bet I could make a Dual Blades/Shield Defense Scrapper

 

It seems like the lock-out method was only "If you've chosen a power from Shield Defense, you can't choose Nimble Strikes" but now that you've opened up Power Strike, I was able to take that. Though it does seem as though I'm locked out of taking Battle Agility as Nimble Strikes as I level.

[Major_Decoy]

Okay, no Dual Blades/ Shield Defense scrappers.

 

Edit: and I was able to make a Battle Agility/ Power Strike tanker, but I was locked out of taking Deflection as I leveled up.

Edited October 5, 2022 by Major_Decoy

[Major_Decoy]

Okay, this appears to be the only set and archetype with this issue. Staff Fighting, Claws, Spines, and Titan Weapons are all inaccessible on all archetypes, and Dual Blades is inaccessible on all other archetypes as long as Shield Defense is selected.