Pulse & The Veins
Pulse is the intangible lifeblood of all living things, the raw energy of creation. In the Vaelniersam canon, it originates from the blood spilled by Valens in the process at the beginning of creation; as the myth goes, the great Guard cut into its body, and so pulse poured out and became the world and life itself. Though humans are "filled" with it in a way that can be sometimes directed and utilized as a kind of primitive magic, it is densest in the Veins that course throughout the planet and well up in select locations; where the "wounds" of world open up before mankind are where humanity is closest to creation. Those who enter become one with the world again, their body and selves dissipating into the flow of energy that maintains the cycle of life and matter on the surface. Over the years, as the population of living things has fluctuated, the size of the Wounds have grown and shrunk alongside it, supplying energy and perhaps also increasing the ease of return.
The outward manifestation of Pulse has only become part of daily life in relatively recent history. This increase may be due to the growth of the Wounds. Otherwise, it was a relatively rare occurrence to stumble across even up until the Southern Campaigns some 5000 years ago, and so the schoolchild's question of "Why would the old armies fight with only swords and spears when there's Pulse?" is negated by the fact that there was not Pulse to be used. Rather, if old legend is to be believed, Pulse was used almost exclusively used by the ancient heroes who became the Observers and the Watchkeepers themselves, in those days where they walked the earth alongside humanity.
Truthfully, Pulse is an odd, unanticipated defect of creation. It sources from subtle seams in what one might consider the "soul," and so, as the energy of life in the world has increased, these seams have widened to allow it to leak through. When these seams "burst," there is either a seemingly irreparable fracturing of the being - or, yet to be seen, intense energy with a vast potential to rival the great Guard itself.
Manifestation of Pulse
The most common appearance of pulse in human beings is to push its flows through other objects. In fact, it is highly uncommon to find a person that is able to use it at will, and it is only a particularly skillful kind of person that is able to do anything substantial with it. In this sense, pulse is merely a potent source of energy for the layman, used mostly for conveniences like powering small devices such as signature locked doors. Many people never learn how to channel pulse at all. Beyond innate ability, one cause of this is the unsolved debate over whether pulse is finite, if it regenerates within the body like an injury closes with a scab or if the scab itself is an exhaustion of it. Some maintain that this is the case and resolve to never use pulse or to use it only when direly necessary, as it can be believed to shorten the lifespan. On the other hand, there are examples of individuals that instead live vastly beyond the typical human lifespan, likely made possible by an incredible manipulation of pulse within their own bodies, such as the Corvethian general Albrect. Regrettably, these are never the kinds of secrets made public to the world, and some of their like purport themselves to be spiritual chosen ones, descendants or disciples of the Watchkeepers and similar figures of folk history, and various other unprovable claims. People of this kind are so few and far between that it would otherwise be dismissable as hearsay if some of them did not reappear before the people every year for governmental affairs and other publicised events.
This can be taken as evidence of pulse manifestations to be able to modify aspects of life itself, the human body. The simple truth is that people of that caliber do not reveal themselves often enough to explain the extent that this can be pushed, but superstitions and urban legends of beings that can shapeshift and exhibit characteristics of things unlike a regular human persist as a result of the thickly grey area between feasability and impossibility when it comes to pulse. It becomes intensely difficult to determine the truth in legends of both the ancient days and the ones we are in now.