What counts for historical artefacts in your fictional world and what relevance do they have to your main characters? Certain stories (Indiana Jones being the obvious example) are full of/based around historical artefacts but in others (The Lord of the Rings) the object is phenomenally important but the real story is the quest. (Okay without the artefact there is no quest but you usually find out more about the characters on the quest and, for me, this is where the real story is to be found).
Historical artefacts can be good or evil magically then, they can also be the cause of war, maybe they can be used to bring peace too. Can they be faked? Medieval times were full of saints' relics in Britain and forgery would have been rife (not everybody can have St. So and So's thigh bone or whatever and it was not uncommon for more than one church to claim to have the same object!).
Who looks after the historical artefacts and just what are they prepared to do to defend them? Why are these items treasured the way they are? Definitely some story ideas there!