I think you are forgetting #4 = dammaged, AKA dog meat.

However, as grading goes, why not just let the strikes be what they are?

Why do we need grades when words are good for each strike.

"it has a line on it"
"It has slight toning"
"like new"
Etc.?

Oh, right, because there needs to be a scale for listing them on some for sale website.

Just about all strikes, in cases are "mint" and the ones that are not, have descriptions to cover why they aren't "mint".

Thank God that someone hasn't come up with a 100 point scale for strikes, so they can become like coins, all contrived in grading to enhance values.