To be fair, 200 year aside, it's pretty much guaranteed that that spear only break in big crisis. It's a spear that only higher up in the family can handle. If it break:
1. From battle, then that mean the big shot got defeated. Family with no big shot in these types of stories don't last long.
2. Economics crisis. Maybe they got bankrupt, and resort to selling it.
Given how Important the spear is to the family it's existence is practical tied to the family.