The most important in my opinion is creativity. You need to have an open and curious mind. Constantly finding new ways to make clothes appealing. Creativity ranges from knowing how to sketch to combining colors and textures to make unique pieces.
Communication and interpersonal skills is very important. You should be able to explain your design in a detailed way to the production team to understand. You will also meet different clients (especially with bespoke) you should be able to keep conversation going and make sure you understand the clients needs. Its also super important in building business relationships with your vendors.
Pattern drafting and tailoring skills are important. Its easier to explain to the production team if you have an idea of how the sketch design can go from a drawing to a 3 dimensional piece.
It’s important to be business savvy. This will help with costing and pricing. You don’t want to waste resources and you want to get the best deals.