From Stealing Creation there are a total of Six differant Item catagory's you can buy from. Body Armour, Leg Armour, Head Armour, Weapon, Proto Tool, and Morphic Tool.
Armour and Weapon Bonus:
While wearing charged sacred clay armour and weapons you will recieve double Xp gained from combat in Either your Melee, Magic, or Range skill depending on what you curenty have the armour transformed into. The Magic armour gives the same stats as Mystic Armour, the Melee armour gives the same stats as Rune armour, and the Range armour gives the same stats as Green Dragonhide armour. Sc Scimitar is same stats as Rune Scimitar, Sc staff gives same stats as a Mystic Staff, and the Sc bow gives the same stats as a Yew Longbow. When Armour or weapons run out of charges they will no longer be able to transform and will no longer give bonus xp until they are recharged. But they will retain their stats.
Tools:
Morphic Tools are highly reccomended over using Proto tools because you can decide what you want them to transform into there for decide what you would like to train. It gives a 2x bonus while the Proto tool gives a 2.1x bonus. The tools they can transform into are Butterfly Net, Fletching Knife, Hammer, Harpoon, Hatchet, Needle, and Pickaxe. You must have at least a level of 40 in the relevent skill to use a Sacred Clay item. (Armour requires 40 Defence, Fletching Knife requires 40 fletching, ect) You can use the trasformed tool with any skill you would nomally be able to use them with. (Hammer can do Smithing and Construction, ect) When your tool runs out of charges it will disapear.