After escaping your cell, kill the Goblin and walk to the table. Look at the pile of garbage in the corner, then take the bone on the left (in the pile of vegetables) and use it on the chair ten times to get new items in your inventory.
When you have to find the Water and Earth Goblin clans, you may find a shop in a cave. Go to the shop, sell every item you can get into the chests, and purchase the Disarm Trap spell. Keep a couple weapons then attack and kill the shop keeper and his brother. Take the key from the shopkeeper and get all your items back, as well as the gold he gave you for the items.
If you have the Bless spell and an Ylside armor, you can equip them even if you are in the 10th level of Strength. Use the Bless spell (your level of magic is important at this point) and equip the armor and weapons. When the spell ends, you can still wear the armor.