You may have missed one of the subquests to get to the Hall of Echoes in your first game. If you run into that problem again, look up 'Hall of Echoes Bound' in the forum, or Dragon Knight Saga FAQ/Guide, etc.

In the battle tower chest there are 2 pieces of the bone dragon set that give you +40% hit points and offence. For alternate set pieces, or mana / defence bonuses, see the topic Dragon Armour (locations only) or the DKS guide above (bonuses and locations).