That works. It'll dry off quickly enough when it's back on Sans later.

"The castle. There's some blankets inside we can dry you off with."

With Frisk situated, he walks toward one of the openings inside.

"So... there's no better way to say this, so I guess I can't dice it. The Frisk I know isn't blind."

Which is nothing against this Frisk's blindness, but he had to start explaining the whole timeline thing somehow.