[DISCLAIMER: CURRENTLY NOT IN THE GAME/UNOBTAINABLE]
The enchant arrow can be found in Treasure Chests, or can be bought for 299 Robux. They cannot be dropped or traded.
You have a 20% chance of getting a High-Chance arrow from a chest.
You have an 80% chance of getting a random low amount of yen from a chest.
Low-Chance Arrows were formerly obtainable, but removed from the chests, however if you stored one in your backpack it likely still exists.
Your stand must be max to use the enchant arrow, and only certain stands can use it. You can find what stands can be enchanted and more about how the enchantment process works here.
If enchantment is successful your stand level will reset, and a message will appear at the top of your screen saying "Successful Enchant".
Each enchant will grant the stand 5% more power, and when the stand is at its highest enchantment level, its appearance will change.
Low-Chance Arrow -
40% Success enchant.
48% Fail to enchant.
12% Reset stand level, without boosting the stand.
High-Chance Arrow -
80% Success enchant.
20% Fail to enchant.
NO RISK OF STAND LEVEL RESET!
Full-Chance Arrow -
100% Success enchant.
0% Fail to enchant.
No risk of stand level reset.
(Note - this is the one that costs Robux, you can't get it from a chest. The other variants cannot be bought using Robux.)
This is a chest, you can get a High-Chance Arrow from this. Just touch the chest for a chance at an arrow.