The Tier 1 Cutlass weapon has the same image as the Rapier in the Equipment section of the Demiplane’s Game Rules. The Daggerheart Core Rulebook provides an image for the Cutlass that, I think, got overlooked, due to the similarity to the Rapier’s image when making the Game Rules entry.
Thanks for catching that. I’ve passed it along so that the appropriate folks can get that image swapped out.