Fishing Guild Leader Santiago:
You need a new Agathion? I can exchange an Agathion Charm +10 for a Greater Agathion Charm.
Bring me an Agathion Charm +10 to receive a charm that summons a Greater Agathion of the same type. You won't be able to exchange it back, so take some time to mull it over.

I can exchange an Fire Dragon Agathion Charm +10, 3 Dragon Essences, 1000 Crystals of Determination, 1000 Crystals of Protection and 1000 Crystals of Dawn for a Greater Fire Dragon Agathion Charm.
But I can't do the exchange if you have more than one charm of the same type in your inventory. You will have to leave all the other ones in a warehouse.
And one more thing: you can exchange a Sealed Agathion Charm, you will need to remove the seal first.
Trade agathion charms