When you first enter the Colchis ruins you'll notice a fairly large number of slimes oozing around. The first goal is to clear as many of the slimes as possible. The best way to do this is to just wander around until you can see the entire map in your mini-map section.
Now it's time to fulfill your purpose for coming to Colchis in the first place. Head down to the Southwest corner of town, and you should see a blank area on your mini-map. Go into the pen that's right beside it, and push against the wall there. You'll find yourself in a secret room containing a friendly Ghost. The ghost will tell you about two items that are concealed in the ruins, or rather he'll tell you that there are two items and where they are.
First head over to the "building" directly north of here. Wander around the tall pillar and when given the option, take the item. This is the Wyrmskin Helmet. When you take the helmet a few slimes will ooze up and ambush you.
Now head over to the building to the west of the paved courtyard. Wander around the anvil in here, and again take the item when given the option to do so. This is the Basic Charm. You can choose on who to equip these items, and you don't have to equip them both on one character, unless you intend to always have a certain person taking all the damage, in which case it would be best to equip them both on him/her.