I have spent a lot of time running a bar of wax over my Belstaff jacket. No longer, now I use spray on Nikwax.
Every now and then my waxed cotton jacket needs a touch up. Nikwax is about 1000x easier to use than a solid or cream wax. You liberally spray this on, rub it in and let it dry. I find it has a pleasant, not noxious scent.
There are two colors: green and neutral. Make sure you check the label, although green will work fine on black. It is a very light tint and won't show through, at least on my ancient jacket.
California's recent rains show this stuff not only goes on easy, but works well.