If the feeling of power is within their bodies, as you say, and they cannot use psionisis outside of their bodies, then how are they to affect anything other than themselves if this magical energy of yours is apparently untouchable except if it coexists in the same area as a psion, which would be impossible unless a psion draws the energy into themselves for use.
The feeling of power can be construed to be internal due to the psion's intake of psionisis. While the psion cannot store psionisis for long term use, they are still drawing in psionisis to use as they are apparently unable to use psionisis outside of their bodies because you assume that no current psions can, while you never seem to really state exactly what using psionisis outside of their bodies would be accomplishing.
You state that psionisis is leaked from streams of psionic energy, therefore a stream of psionic energy can be thought to also be a stream of psionisis. Psionisis would slowly leak from the psionic energy streams at all points, creating a constant stream of psionisis from the psionic energy stream.
The latter half of the paragraph is foolishness. There are no more practical ways than a psion, and psionisis cannot be integrated into technology because it only responds to psions and other psionisis.
[from the psionic treatise]
The psionic currents can be indirectly tapped by two fairly common methods. The first is to bind a current to an object, ensuring that one’s source of psionisis does not shift its course and leave one without a renewing source of psionic energy. Only very accomplished psions are able to bind a current to a small portable object. The second method of tapping a psionic current is a psionic converter. This is a specially constructed and psionically attuned device that accelerates the conversion of raw psionic energy into psionisis.
These are two examples of some sort of technological object being utilized to affect psionic currents in some way to provide psionisis. By your own words, you contradict your treatise. You also mention psionic amplifiers and such, too. More contradictions.
Also, the length of study does make a difference because the only tool required are psions. In order to use psionisis, a psion must be able to sense it. No matter where that feeling comes from, even if it may feel as if it is coming from within a person, they are sensing psionisis. Being an Aegrus naturally heightens all senses of a person, all the time. Your treatise covers psions that seem to be standard lifeforms, but the Aegrus are hardly standard lifeforms. Sara is the most powerful Aegrus psion, and she is behind the leader of the psionic research division. You say that only immensely powerful psions are capable of directly manipulating psionisis outside of their bodies? How do you know Sara is not one of them? You never really define what manipulating psionisis outside of their body would provide for a psion. Being the creator of the treatise on psionics does not make you the sole commander of everything psionic. You cannot tell us how powerful our characters are, nor how powerful they may be. That is not for you alone to decide.
It is also not for you to decide whether or not any current character can manipulate psionisis outside of their bodies. You created the psionic treatise, not the psionic characters. Do not overstep your bounds. Also, do not bother retorting with, "Well, I have seen no evidence of any characters doing it thus far" as that rebuttal would be insubstantial and nullified by the fact that our characters had no reason to exhibit these characteristics beforehand because your treatise was not accepted as a law of the AETAS world until recently.
Research into what a psion lost in space with low psionisis concentration would indeed yeild interesting results, as you fail to see. The Aegrus do not follow superstition. They have been subject to so much superstition themselves, that they refuse to accept superstition or unfounded belief of a physical or physiological matter without hard proof. If an Aegrus psion went from point A with high psionisis concentration to point B with low psionisis concentration, they would immediately realize that something was different and that something changed. It might feel internal, but they did nothing and they feel no other change in their bodies. The Aegrus psion would then search as to what exactly caused this and, in doing so, return to point A to see if whatever changed does so again. They would find that it does and they would thusly further investigate the matter. Aegrus study into various genomes and an immense ongoing genome project has yeilded mild results in the matter of genetic psionic ability research. While not able to grant immense, or even moderate, psionic ability to modified or constructed lifeforms, a very minor ability can be generated. Comparing complete data of two genetically identical, except for the presence of psionic ability in one, lifeform constructs could easily show no physiological or neurological change between the two in either point A or point B.
It is easily discoverable in near a millenium that psionic ability stems from within, but is not powered from within, unless you count being powered by drawn in psionisis to be powered from within.
Aegrus psions conducting "scouring searches" of their minds are not very similar to normal psions conducting scouring searches of their minds. Aegrus brain and thought structuring, as well as DNA and genome structuring, are vastly different from average sentient beings. The Aegrus's DNA has more bases and a more intricate structure than average bioforms, and their genomes are often completely different than that of average bioforms. Down to their molecular level they have been changed by CM. Your treatise and assumptions may hold true to the average bioform, but the Aegrus are far from average. The number and magnitude of their physiological changes dwarfs the number and magnitude of the abilities that are gained or enhanced.
When an Aegrus feels a major ability of theirs suddenly wane and lose most, if not all, function, they do not assume, "Gee, I must be tired." Especially so when they have not been exerting themselves or even using their abilities, and have just passed from one locale into another. Heightened senses do not just refer to sight, sound, touch, taste,and smell. Heightened senses refer to every possible aspect of sense. An Aegrus would know the second a blood vessel burst in their bodies, no matter how small, and would know exactly where it was. Their senses, the ones pertaining to themselves at least, are extreme.
I enjoy this discussion, however, as I feel it is helping us further understand exactly what you mean by certain things in the psionics treatise.