To begin, let me just say that I differentiate between a talisman, amulet, ritual implement, and relic. A talisman is a mystical item, charged with energy to attract to the bearer. An amulet is the same item, but to repel. A ritual implement is typically a conduit of energy, used in ritual to connect you immediately with that current so that you may amplify your working.
But a relic, the focus of this post, is more than these things. A relic is something truly sacred, truly divine. A relic often acts as a portal from our dimension to another, depending on who the relic is sacred to. For instance, I possess a relic that was once a sword used by a magician to spill a lot of blood. Now, it acts as a doorway into a dimension of pure rage, and pain. Then, there are relics that act as vortices of energy, such as the Ossuary of Canaan, which both attracts and generates the energy of that current.
These relics are often the products of members of a priesthood creating them for a certain purpose. The Ossuary of Canaan is a perfect example of this, these items are only produced by members of the Priesthood of the Shadows of Death. Similarly, the Staff of Patricide is only formed by members of the Order of the 13th Judgement. However, it is possible to create such relics on your own, without being a priest. The general rule for relic creation is, they are not common amulets or talismans. These items are constructed of the rarest ingredients and dedicated in the most sacred rituals.
Relics can be custom created, as I have done before, but creation of these relics is not easy, and can be quite costly, especially since a lot of relics rely on human necrotic material, which is not exactly easy to get. If you have the money, contracting someone to create a relic for you is a great idea, as you know it will be done well, but if you have the time, energy, and experience, it may be in your better interest to form your own relic creation ritual.