[ giorno purses his lips, clearly reluctant to reveal what it is, until he just finally says, ]

... It's a Stand.

Most of the time people shouldn't be able to see it, and for good reason: it's a rather personal thing. It's a reflection of the user's soul.

But things are different here so I probably should just let it go.

Personas sound very similar, however. It isn't really surprising that even in different worlds, the means of summoning may be different for people but the principle remains the same.