Celestial Weight

Also known as Celestial significance, or sometimes just significance   Essentially, Celestial weight is the measure of how much Celestial energy a given idea or entity owns. Every individual soul has a certain amount of significance simply by existing. Magically charged actions increase the significance of relevant parties. Significance can be thought of as a measure of Celestial mass, higher amounts resulting in a soul with more influence.   Killing is an inherently magically charged action because it involves snuffing out a soul's vessel, an object essentially composed of significance. This is how objects such as weapons can gain significance despite being seemingly inert. There are other, less questionable, ways to affect significance, but killing is the most commonly discovered in cultures due to its intuitiveness.   Celestial weight, on its own, has a very subtle effect. As a general rule, it slightly reduces the chance of something of significantly lower significance from affecting the concept/object in question. Some cultures have superstitions regarding the concept, although they have no correlation with actual observation of the effect- significance naturally plays on the human desire for things to fit neatly into patterns. The exact mechanics of this are very poorly understood, see The Soul-Force Effect.   One side effect of significance is that it makes enchantment far easier to anchor to an object. Typically, the green quanta component of enchantment references the given object as its general type, along with a metaphysical giant pointing arrow saying 'this specific one'. The more significance an object gains, the less Celestial one would have to write to create a 'pointer' to it.  

Visibility

The less perceivable something is, the less Significance it's charged with. This generally amounts to visibility and timescale: flashier things and slower things have more Significance. Extremely fast things often 'go wrong': projectiles faster than the sound barrier seem almost magnetically attracted to the most armored parts of their targets.   Many martial arts utilize seemingly excessive flourishes designed specifically to take advantage of this effect, 'charging' one's actions with more Significance. Fast-moving projectiles from firearms would have their Celestial impact even further neutered by this effect, along with their lack of The Soul-Force Effect.  

Physically quantifiable effects

Thinking of Significance as mass, one could think of its physical effects as the resultant gravity.   Significance causes very slight shifts in reality based on what's already possible, pushing one towards 'best case scenarios' more often. This can be interpreted as luck, though it can be used for much more. It breaks causality, adjusting the physical reality to better meet expectations, with a degree of influence based on how much Significance is available. Clairvoyants are notable for being capable of consciously doing this. When two Celestial bodies act against each other, the Significance differential determines which side is more likely to get the favorable outcome.   Overall, Significance is essentially a Maxwell's Demon driven by consciousness. Things just work out better than entropy dictates they really should. Note that the consciousness is explicitly divested from the physical reality, so it's not just part of a larger physical system. The Celestial reality doesn't actually share this concept of entropy (note that causality doesn't really work the same way in it either), so trying to define it as a cross-reality system just gets really dicey.   As a result of its broadness in application, Significance is unspecialized, and therefore inefficient. In its natural state, Significance is an amorphous aura that permeates and envelopes the soul. As a form of Celestial energy, it can be converted, crystallized, into more stable and specific structures. However, being the most incorporeal form of Celestial energy that retains any degree of coherence, it's hard to grasp and manipulate. For example, the entire practice of collecting Oaths by Whirlpool stems from an inability to manipulate Significance in its most basic form: at the very least, it has to be calcified into something more tangible and brittle so that pieces can be snapped off and extracted by Contractors.