Xanafir

Xanafir
The Xanafir is an object that contains all of the multiverse. Every universe - which there are many of in the Elithian Alliance lore - is contained within it, but at the same time, it is a physical object that exists in the multiverse, and it can be manipulated with the right tools. In the lore, only the Centens ever managed to achieve such a level of technology, and the Theleans strive to reach that level of technology themselves. (Which is the short version of why they hunt for Centensian relics.)

The Shards of the Xanafir are objects that are directly linked to the Xanafir, and are able to draw from it's nearly infinite pool of energy. The Xanafir itself was never broken - that might not even be possible - but the Shards were given their name as they can only draw upon a small portion of the Xanafir's energy. They generally take form of a crystalline material, and often look like they were broken off a larger piece of crystal. (Which further explains why they're called Shards.) With their anomalous properties and psychokinetic energy, Centens rely on as a power source for most of their more advanced technologies.

Shards only allow a finite amount of energy to be drawn from the Xanafir, and only in small amounts at a time, but they can still be extremely powerful and are extensively used in Centensian technology. The Avikan have been able to use the Shards to a limited degree, too, as can be seen in the Vha'leihan Spear, but the Avikan never managed to find large amounts of Shards and so have only limited knowledge on how to use them.

Xanafian crystals are made of pure Hyverium, so they're the same thing. A Xanafian crystal is just a large collection of Hyverium particles, which tend to create crystalline forms in larger masses.

The Xanafir appears to be natural, but no-one knows for certain. It's older than any known civilization, but its true origins are likely impossible to know.

Xanafir could do calaclysmic things in wrong hands. At the end of the original roleplay, it was actually responsible for an event known as the Blast, which was a multiverse-wide release of energy that nearly caused the destruction of the entire Elithian Alliance. The effects of the blast were mitigated somewhat by certain precautions taken by the Centens, allowing the Alliance to survive and rebuild, but the event still ravaged many worlds.

For "Starbound", the Elithian timeline was altered in some places and the Blast never happened, but if it would, it could threaten all known life.

What if for Xanafian weapons clashing. It depends on the types of weapons and exactly how they come into contact. If you have two bladed weapons infused with Xanafian energy - like Vha'leihan Spear - having them clash into each other. If one were to hit the actual Shard on the other weapon, that's a different story: it would most likely break that Shard, releasing a massive amount of energy at once, creating an explosion that could kill anyting within it's range. The size of the explosion will depend on the strenght of the Shard (or rather it;s conduit to Xanafir), but it'll be deadly regardless of it's size. The Shards are extremely difficult to destroy through regular means, but a Xanafian-powered blade is one of the few things that can reliably destroy another Shard.

Xanafian damage
Xanafian damage is a bit of an odd one, and it's Starbound implementation isn't completely canon. (In general, the Starbound universe uses more fantasy elements while the canon remains a bit more grounded, like how teleporters don't exist in the canon either.) In the mod, Xanafian damage would feel a bit like burning, stinging sensation and it applies the shadowmarked effect. A shadowmarked entity is connected to paralled universe, and when they die, it causes that connection to 'open up'. This allows some of the Xanafian energy from that parallel universe to leak into ours, creating a construct of energy known as a Xanafian Shadow. What that is, exactly, is unknown, but many believe these shadows to be semi-sentient and potentially linked to a parallel 'soul' of the deceased.

Xanafian Shadows
No one knows what they are exactly. A Xanafian shadow is created when a living (usually organic) being is killed while affected by Xanafir. Energy is pulled from a parallel universe and is concentrated into the construct of energy we see as Xanafian Shadows. These constructs are unstable, hence why they decay after a while, but there seems to be a form of sentience to them. Since these Shadows are only created when living beings are killed - and not when robot is destroyed, for example - some believe these shadows to be parallel souls. Again, no one currently understands exact mechanics at work here. It's possible even the Centens weren't fully sure what the Shadows were, despite their ability to summon them at will.

Interestingly enough though, the Centens have created AIs that do produce Shadows, which might be due to the use of Xanafian Shards in the functioning of these machines.