Bullets, blunt instruments and sharp objects, yeah Mages suffer all of the usual human weaknesses more than other splats.
Beyond that I would only see adding an additional, material bane if the antagonists in the chronicle are intended to be normal humans but in that case I think a bane that serves to protect the antagonists from magic information gathering would be the best use. Something that denies a Mage his greatest strength, the ability to prepare and plan ahead.