Renaissance wax might do the job, although I haven't tried it.
Edit: From Wikipedia - Renaissance Wax is a brand of microcrystalline wax polish that is widely encountered in antique restoration and museum curation. Although not appropriate for all materials, it is known to and used by almost every collection. It is also used as a primary finish for cabinetry and furniture. Renaissance wax is also used by reenactors of historic swordsmanship to protect armour and weapons. It is widely recognised that this substance is more protective and longer lasting than oil, especially for swords and helmets that are frequently touched by human hands.
Last edited: Apr 17, 2013