If you have wood handles you may want to avoid getting it on it. In a different thread, it was mentioned that oxygen plays a role in the patina formation (oxidation), so don't put it in a ziploc either.
I tried mustard on a wood handle Barkie and I think it ate some of the wood finish off. I'm sure someone with more experience than me can chime to tell me I'm right/wrong. It was my first attempt.
If you have G-10 handles you have nothing to worry about, IMO.