I have this weird theory that I'm gonna just throw it. It's utterly baseless. I'm spitballing, honestly.
Okay, in Volume 4 (I think) Weiss says that Whitley never got the Glyph semblance the women in the Schnee family have. But, what if somewhere along the line he gets a Semblance of his very own. I mean, something unique to him and him alone.
And what if that semblance is summoning a snowman.
Okay, not an actual snowman, just like summon, that happens to be snowman shaped. A Stand, okay?
And what if that's Whitley story allusion? That he's one of the kids from Frosty the Snowman, with the power to summon Frosty whenever he wants.