Saint Silvan died 350 AD and despite the fact that his body was never artificial preserved, it has never decayed and shows no signs of starting to do so. The reason his body never decayed is because he was embodied with eternal youth, which he received from an archangel, likely due to being a prophet. Every generation has one prophet and each prophet, in exchange for their complete allegiance to Heaven, is granted anything they desire under the condition that it does not involve living forever.
Saint Silvan asked for eternal youth, which he was immediately given. Afterwards, everything he had been wearing at the time was infused with the same power. After having possessed the power for so long, eternal youth became Saint Silvan and Saint Silvan became eternal youth; they were one in the same thing and he completely stopped physically aging.
This item was worn by Saint Silvan when the archangel blessed him with eternal youth. Since then it has been refurbished only once but it remains the original piece and the power within has not been harmed. Like Saint Silvan, with prolonged exposure to the eternal youth, you will eventually reach a point where you no longer need the item or any item that grants youth for you to be immune to time and its affects on living creatures.
For now, this item will preserve you in your current state. You cannot go forward or backwards.