[Jotaro Kujo]

The W, OOO, Fourze, and Wizard Lockseeds say "Kamen" and the rest say "Masked" for the same reason Figuarts boxes do.

Bandai made a conscious effort (and I think it may be a branding effort) to use Kamen from W on, basically. It's nothing at all new.

The reason it seems as if it is DX and not the others, is because, funny enough, the W, OOO, Fourze and Wizard Lockseeds are the only DX Rider Lockseeds. But it has nothing to do with what kind.

Also, by going two slashes / three slashes, etc., you're actually cycling through the first two sounds again, which is how the Gashapon / Candy / Bandage Lockseeds work, they don't work like DX Lockseeds.

the sounds go Ryuki, Ryuki Arms, and then one of the attacks, depending on how many slashes you do afterward. Like so...

Ryuki

Ryuki Arms, Tatakawanakereba Ikinokorenai (Those who don't fight, won't survive, the series's catchphrase)

and then depending on how many slashes you do, one of the attacks.

Repeat