I pictured Vesper as wearing a british naval uniform, see "Master and Commander”. Hollin navy colors (not sure what those are at the moment). The coat typically hangs open revealing the chain mail coat he wears underneath (he’ll button up for formal occassions). He hangs his maul across his back which is attached to straps that he can yank to quickly bring it to bear, and has a satchel attached to his belt that contains medical/first aid equipment. Normal navy dress trousers, boots. Naval cap.