I used a random number generator and a list of weapons and items (and their rarities) in Fire Emblem Radiant Dawn and came up with items for the five chests: 
Top left chest: Secret Book
Left vault chest: Mend
Middle vault chest: Bronze Axe
Right vault chest: Purge
Top right chest: Venin Bow
Does that sound reasonable to you, or would you rather decide what is in them?