Final fantasy question?

ok first before I start there will be spoilers! so if you haven't finished final fantasy 7 crisis core or dont want the the end spoiled dont read! anyway at the end of crisis core zack dies on like the edge of a cliff. and later cloud puts the buster sword where he died kinda as a memorial for him and then in advent children cloud is standing there and the sword is all rusted and scratched! angeal and zack wanted to preserve the sword so if cloud wanted to respect zack and angeal he would put it away somewhere right? please if someone can explain why he would do this i would be so thankful!