Could Aons damage shardplate?

[Adonalsium'sSpren]

and could AonDor be used to make a shardblade?

[Honorless]

Seons can be pulled more into the Physical to do the same thing that Spren do, so they can take the form of a Shardblade or something similar.

AonDor should be able to do something similar too with how versatile it is, but presently we don't know which Aons might be required to pull it off.

Aons should be able to damage Shardplate.

[RShara]

Shardplate isn't indestructible like Shardblades are. They can be damaged with regular weapons, it just takes a lot more. So an Aon that creates a destructive or blasting force would be able to damage it.

For Shardblades, it depends on your definition of Shardblade. An Invested sword? Sure, AonDor should be able to make one. An Invested sword that can cut on all three Realms, severs the soul and so forth? Maaayyybbeeeee. We don't know enough about it yet. It's also possible that seons could manifest as a type of Shardblade, but no idea what their powers would be, either.