So, if provided with the proper materials, why couldn't he make another?
Quest writing isn't my forte, so it may need some edits.
The first time you do it, it will be explained; but in repeats, it should be brief
(yes these quests should be repeatable)
A few required quests:
finished id 626, found in file 277 - this is the orc on 4.0, and id 626 is where he gives you the first enchanted ring
I'd like to include another npc, and I don't think this one is used for anything else (idk, might be in coming update)
finised id 287, found in file 264 - this is the mage npc on 3.3, where you've finished his quest to slay dragons
Approaching the orc on 4.0, a conversation arises:
chat_me: Hey orc, I wonder, could you enchant another ring for me?
chat_npc: Well, I could, if I had the proper materials, and you compensate me. I have more debts to pay.
chat_me: Tell me what you need.
chat_npc: Most of it is basic materials, but the magical essence I do not have, and cannot make.
chat_me: How can I find this magical essence?
chat_npc: I only know of one who knows how to make it. A powerful mage who studies dragons.
chat_me: Ah, I believe I know of this mage. I helped him once before.
chat_npc: This is good news! Tell him you need a potion of spectral essence, and bring it to me.
chat_npc: Also bring me a wooden ring, a ruby, a diamond, 3 golden ingots, and 300m gold for my time.
quest_log: See the mage for a potion of Spectral Essence.
quest_log: Bring a potion of Spectral Essence, a Wooden Ring, a Ruby, a Diamond, 3 Golden Ingots, and 300m gold to the orc to get a powerful ring.
Approaching the mage on 3.3, you ask about the essence:
chat_me: Hello again magus, I seek your help.
chat_npc: Greetings! Again I thank you for your past help. What can I do for you?
chat_me: An orc is going to help me enchant a ring - but he needs a spectral essence potion.
chat_me: He said you may know how to get this.
chat_npc: Yes, I could make this for you. But you will need to collect the ingredients.
chat_me: Tell me what you need.
chat_npc: It is a combination of elements. The base is made from 3 spectre dusts.
chat_npc: I will need a scroll of Yellow Flow magic and a Red Mixture as catalysts.
chat_npc: One chunk of Mithril ore, to be ground into the mixture. Two chunks of carbon to increase flammability.
chat_npc: And I'll need something to put it in - a 1000 HP potion bottle will suffice.
chat_me: It will take me some time to gather all of this.
chat_npc: That's fine. Bring me the items when you have them.
chat_npc: I will charge you 100 million gold for my time.
quest_log: Bring 3 Spectre Dusts, a Yellow Flow spell, a Red Mixture, 1 Mithril Ore, 2 Carbon Ore, a 1000 HP potion, and 100m gold to the magus.
needed items:
3x 323 Spectre Dust
203 Yellow Flow spell
265 Red Mixture
260 Mithril Ore
2x 258 Carbon Ore
300 +1000 HP potion
100m Gold pieces
and speak with the mage on 3.3 again
chat_me Hello magus. I have the items for the spectral essence potion.
chat_npc Very well. I shall make it for you immediately!
chat_npc (The magus turns his back to you for a moment, you see various flashes of light)
chat_npc (A distinct burning smell is noticed.. and the magus turns to face you again)
chat_npc Here you are! This is easy enough to make, so come back if you ever need more.
chat_me Thank you magus.
at this point, the magus gives you a new item - Spectral Essence potion. It should be a recolored 1000 HP potion, and I would suggest dark in colour.
with the required items, you can speak to the orc on map 4.0, and he can craft you a ring.
needed items:
(NEW ITEM) Spectral Essence Potion
79 Wooden Ring
586 Ruby
267 Diamond
3x 69 Gold Ingot
300m Gold pieces
chat_me: Hello orc, I have the items required to make an enchanted ring.
chat_npc: Did you bring the 300m gold as well?
chat_me: Yes, I have it.
chat_npc: Fantastic. This will pay off my debt, and a little extra for me.
chat_npc: Give me the items, and it will be done quickly.
chat_npc: (The orc places the ring on the ground, with the ruby and diamond in the center)
chat_npc: (He arranges the ingots around it, and pours the potion on the items while reciting a strange spell)
chat_npc: (A large purplish flame bursts forth, and a flash of light - when it fades, the new ring is there)
chat_npc: Here you are adventurer. I'm always looking for gold, so come back again if you need to.
chat_npc: I can do this with the proper ingredients, but do not forget my gold!
chat_me: Thank you for your time. I will keep you in mind in the future.
at this point, the orc npc gives you an item 540 - Enchanted Wooden Ring.
Well, that's my idea on how this item could be added to the game.
Of course, a much simpler idea would be to add it as a rare drop somewhere... but this quest seems to fit more with the existing storylines.
Maybe the above needs tweaking, but it would be really cool to have a way to obtain this item

I'm fairly certain my IDs above are correct, but please double check.
EDIT:
some possible suggestions for what the spectral potion could look like - keep in mind it should not be mistakable for a mana or HP potion; I copied the matrices manually, but I think I did them right
- One: Show
- Two: Show
- Three: Show