Anvils are Assets that can be acquired and are used for completion of rare Weaponsmithing and Platesmithing tasks or as optional components that will improve the chances of receiving a higher tiered result upon completion of a rare task.
A [Worn Anvil] may be purchased for 50 from M'tari Prin'tal in Protector's Enclave (North corner of the Seven Suns Coster Market). Anvils of higher tiers may be acquired from [Professions Booster Pack] and asset packs purchased in the Zen store. Anvils are not bound and may be traded on the Auction House or transferred between players.
A task requiring an Anvil as an asset will take any tier of Anvil in its slot. Higher tiered Anvils serve only to improve the chances of producing a higher tiered result in rare tasks for which they are used.
At Profession Level 3, 4x [Iron Anvil] can be upgraded to produce a [Steel Anvil].
At Profession Level 4, 4x [Steel Anvil] can be upgraded to produce a [Mithral Anvil].
There is no task that will allow a [Worn Anvil] to become an [Iron Anvil].