[Malms, being a very small person himself, is splashed up to the knees (his main protection against the rain being a hat that extends out past his shoulders), but he smiles reassuringly at the child.]

It's all right, don't worry about it! I can dry myself off easily enough. Would you step back a bit, please?

[When Frisk does, there's a bit of a 'woomph' and a flash of fiery light, and the black mage's clothes are dry.] See? All taken care of.