They are a part of a quest. In one of the villages, you can talk to a dwarf about an Axe. He will sell it to you for 10 000 gold. This axe is upgradeable depending on which obelisk you touch first.
You can find some info about the upgrades and the stats you gain from them on the forums. Lvl 3, depending on the type, can provide +5 atk and other bonuses or +7 Def and additional bonuses.
__________________
|