Yata

Nevermind, it's a quite unclear topic, we never sees a whole Shard without an holder (for more than some seconds or minutes) and therefore we can't have direct experience of this kind of event...the best we can do, is to try to speculate with the few element we have My point was just about how a Shard may keep doing is work (if it keep doing for a while) also if the former mind is no more. This point to a Shard who don't explode in a tons of Splinter if lefted alone for too long and it's a basic level of mind to direct its own power if you think about. I don't want to go further on the matter because I don't want to talk of something that may be spoiler to you....But there are elements who suggest that a Shard without a Holder (I decide that I will called it Orphan Shards) also with an hypotetical mind would prefer to have a real holder than keep without. In the end this post of mind made me come to an Idea about Adonalsium and the event of the Shattering but it's too soon to expose it

Actually this isn't really true...the only Splintered Shard we saw are being actively Splintered (most by Odium) as Mistborn trilogy shows....the Shards without holder are not really troublesome...they are there waiting to be pick up because the "power want to be used". We also see how Preservation wasn't automaticaly Splintered when Leras died also if it's what Ati wanted (and Ati is a big malicious force at this point aganist the Shard). We have also some WoB who said that if a Shard is lefted without a holder he may began to develop sentience or keep doing what he was doing before (for example the Mist on Scadrial or the Returned creation on Nalthis). Anyway I think the answer is simply "no Shard was left alone too long" and that a Shard auto-developed Mind is still a worse controller for the Shard's Power than any mortal. It may be that an Autonomus Shard began to search for a new host (to better use its own power)

But actually to get (almost) 50 Metals we have to have a single Alloy per metal. (facts) 16 mundane metal+16 Atium-Mundane Metal Alloys +16 Lerasium-Mundane Metal Alloys + Pure Atium +Pure Lerasium + Harmonium =51 Metals. (Speculation) Of couse the interaction between God Metal maybe create another set, for example if the Hamornium is an alloy of Atium and Lerasium. It may have another set of 16 alloy with the mundane metals probably (and the Metals count rise to 67) . (wild speculation) But this may work with whatever couple of theoric God Metals...There would be an alloy Atium-Skaidium (fictional name) if the Skaidium was avaliable and the Skaidium alone may work as magical Metals or with a set of 16 Skaidium-Mundane Metal. PS: I have to say that more I type "Skaidium" more I like the name

Well we know it's possible to steal Surgebinding therefore the Atium is a good candidate. Instead is impossible to store Breath because it's "too physicalt to work with Hemalurgy (that steal piece of SpiritWeb) but you may steal a Divine Breath

I will try to find the reference from the book, but as far as I remeber it's like "he suffered the oathbreak but survive from his own". I think Tanvast's Shadow merged with a compatible Stormfather to give to it a indipendence to keep fight in the Physical without a RK (they left before this point) EDIT: Ok I found the reference, but I can't post it (my book is in another language). It's in the chapter 75 of WoR and as I remeber is made by Pattern. It's like (not exact wording but a letteral traslation):

Harmony did actual nothing...It was Wax who tapped Health from the Band and "resurect" himself....Maybe the only thing Harmony did, is to be a motivator to Wax and give it the information for his revival (He let Wax listen the Physical Realm and Marasi).

There also a direct reference in the books (I think it was Pattern) who said the Stormfather suffered an OathBreaking....and the Recreance was before Honor's death

I will just add another information to the already good explaination of @The One Who Connects and @kenod. You already "saw" another "misterious metal" that don't fit your Magical-Metal Knowledge (16 mundane metals and 2 god metals). It's the Malatium (knowed in the Mistborn Trilogy as "the eleventh Metal"), this metal could exist for a peculiar feature of the god metals. They may be forged into an alloy with everyelse metal of the 16 (the mundane metal compatible with the Metallic Arts) and indeed the Eleventh Metal (or Malatium) is simply an alloy of Atium and Gold. This mean that every god metal offer 16 new alloy to the Metallic arts (but before you ask we know just the Allomantical effect of the malatium and the allomantical effect of Lerasium Alloys that create Mistings instead of the flexibility of the pure Lerasium).

Relevant WoB: About the Feruchemical Strenght, I will avoid to say more because we had not actual any kind of proofs. And about the Ability to Store/Tap the same metal at the same time is one of the Question I have to do to Brandon when He came here next month (I have a theory is the Full Feruchemist's Perk but it's really dictate by the need of find a perk to them, nothing really worty)

Actually seems the facts seems more to point with "shardworld number" than "shard number" but this indeed a not strictly rule

Actually Vin isn't a stronger allomancer than Kelsier, she was just extremely skilled and intuitive with its use....but this is off topic. Indeed I think you have right about the "Feruchemical Strenght" or to be more precise about the lack of it....but we have not pratical proof. Once I thought "Feruchemical Strenght" was about "how much I may store" but of course if people like Wax may store at 100% it have to be wrong. BUT there is no way to figure if a Ferring storing an attribute recive an equal Feruchemical Charge than some other Ferring....It's hard to compare this kind of thing, more from an in-world PoV

We have to wait The Lost Metal but I still find likely the theory that Lerasium Spike keep everything with a Preservation Related effects (for example a not-decay or the ability a Spirit-Web without steal it)

Yeah probably we have just some implicit information. Like the fact that people murdered are fresh new as Returned or the fact that a piece of alluminium in the body would prevent that wound to heal when the guy Returns.

In my own opinion Listeners changed form before H&C arrived on Roshar...Then something change and they have to find a new way to obtain the Forms, at this point the Unmade arrived and offered new Spren for the Listener who they began to workship as gods. The Spren "betrayal" may be caused from H&C who taint some spren with their Invesiture changing them or something like that.

But it's not something we already know ? I am bit confused

You may try to broke yourself in another and less lethal way...for examplea Twilight's Saga Marathon followed by the Blue Ray's extras

At least He will be an Huge source of Informations on the Listener

Well I always thought they were the Unmade...have we some information againist Listener Gods=Unmade ?

As @Jondesusaid it's possible to obtain Allomancy through Medallion and when you uses a Allomancy-gift-Medallion still need Metal to burn (I will fill weird otherwise)

Well the Elantrian have some Advanced Realmatic knowledge and they used to send thing/people in the ravaging Dor...Or they are sadists-masochists or they can still reach the Beyond

Gravity Falls

I am quite confident that you may send an email or a tweet to Isaac for things like that

Of course there is also the Vivenna died of old age or other causes to add to the list (there are some centuries between Warbreaker and SA)

Shades are only weird Cognitive Shadow...I think Nightblood may consume them and as I said before a Shardblade maybe may cut them

(Evil Yata ON) May I have an Upvote (or tons of them) ? (Evil Yata OFF)