Oh ~ I'm so sorry! Is there any patina on the strap at all yet, or is this strap new?
I have tried using a white eraser on a spot on a handle and it lightened it; did not totally remove it. However, this was not new vachetta, had some patina to it, so I didn't worry too much.
I'm not sure this technique would work for ink ~ I might worry it would rub it in more.
I have used Baby wipes before on dirty handles...... ?? But again, this would depend if you have new vachetta or something that already had a patina.
Maybe someone else will come along who has had experience with ink. Good luck!