Metallic content of your inventory - if you have any - will tally up to a total magnetic "strength". This does not mean much, most of the time, since you are unlikely to be affected by strong magnetic forces. There are certain professions, however, with powers over the Earth; professions able to twist the magnetic draw of a location or an object. When you encounter these magnetic focal points you may find your very movements slowed-down or even halted by the force of the attraction; and metal-containing objects from your inventory can be dragged out of your very hands.
It is possible to discover the magnetic strength of your inventory by seeking a diagnosis from somebody with the Healing skill; or by using the Itemlore PROBE ability (providing your skill is high enough) to examine all your inventory and make your own total - to determine how concerned you should be about heightened magnetic attractions as a weapon to be used against your freedom of movement, particularly on the battlefield.
See also HELP METAL for information about Avalon's metals and their forging.