Abstraction is the secret! I think a big part of this community of DND players have more than 30 years of gameplay like me. I've been DM for over 20 years and now I can play with a character I built to build! My Gnome Wizard (Mergim Weeble) can build magic items, we use Eberron rules with some simple modifications. My gnome has many Clockworks designs, some of them already built. One of the projects deals precisely with this, replacing a lost limb. I use magic items as examples, in our game, it would be possible to have a limb substitution for an Attuned item with some power, such as: An arm with the power of Ring of resistance, for example. This does not change anything in the mechanics of the game. It remains an attuned and flavored item. Maybe a strange reaction, damaging social tests (Disadvantage) for example. Your DM has the vision of it, it's normal, every GAME IS A WORLD! I hope you can recover the arm of your character.

This is a fabulous idea! As i said in my last post, I'm going to confirm with my DM if there can be any mechanical replacements. But I like your idea of re flavouring a magic item as a limb replacement, since (from what I know of) most magic items are balanced. So that will eliminate the need to toss back and forth over balancing this or balancing that. 

Thanks for the feedback!

 PS. I'm a light cleric, and my patron deity is Helm (The Vigilant One), His main symbol is a gauntlet with his holy symbol (eye) on the palm (link to wiki page here https://forgottenrealms.fandom.com/wiki/Helm) I'm thinking of voicing the idea to my DM that I pray to Helm and he either gives me one of these gauntlets imbued with holy magic so that i can place it on my stump or i have to go on a small sidequest to find one of these gauntlets for him (and I keep it in the end) Anyway, what do you think? is this an ok idea?

I think it's a good idea, since you do not change anything in the system. And I have one more idea, as Helm's symbol is the gauntlet with one open eye, and you play with a light cleric, how about using Lantern of Revealing. The same effect as the Lantern when you point the palm of your open hand and the eye opens! Think About it. Its a Uncomon Item, you just need to edit it to get attunement. better, just consider you now have only two attunement slots.

PS: Since you are literaly wearing a Holy Symbol, you could even use to cast your spells.

 I am in love with that idea, the next time I see my DM is Monday so I will defiantly have a chat with him about it. The Lantern Of Revealing is an item i am semi-familiar with (a fighter in my last campaign had one, but hardly used it). I think it fits the light cleric perfectly (since it's literally light) 

And it will be useful since... Well, the current campaign I'm in has two half-elves, aasimar (me) and an elf. Which all have darkvision... well until we introduced a new guy half way through the campaign and of course he had to be a human fighter! So the gauntlet/lantern of revealing (which i have now named "The Hand of Revealing") will be useful. Even though I can cast the light cantrip for him, It will be great to see the odd invisible enemy if we encounter one. 

Thanks for putting the effort in to research a bit for me, it's really appreciated!

Ok, here’s is the item for you, just make a copy for yourself and give it a history. 
https://www.dndbeyond.com/magic-items/729070-helms-hand-of-revealing

Good luck on your quest.

Thanks, made a copy and added a history. 

Can't wait to ask my DM!

Take the hand of a powerful, fallen enemy and attach it.
Much RP potential.

Buy one on the black market.

Create a new one through arcane methods.

Make a deal with a patron, take one level in warlock, get a demon arm.