(as) graceful as a swan
Very graceful or agile. That ballerina is as graceful as a swan when she moves across the stage. A: "Oops, did I knock that over?" B: "Yep. You know, you're not exactly graceful as a swan, buddy."
*graceful as a swan
very graceful. (*Also: as ∼.) The boat glided out onto the lake as graceful as a swan. Jane is graceful as a swan.