Where Anyone is Possible
Each type of energy; be it magical, non-magical, or even a non-energy such as Void or Anti-Magic; has its own particular "energy signature."
That is to say; each type of energy has a different feel and 'presence' or 'aura' to it which some beings are sensative to and able to learn to sense or detect.
This being said; every -person- has their own energy signature. Even identical twins with identical abilities would have a different energy signature; being as they would have a different -life- energy; being pheremones, hormones, and other such biological factors which differ even in identical twins.
Energy particles are subatomic particles that are constantly being given off by an energy signature.
For example: When Xander casts a fireball and it dissipates. It leaves behind trace particles of fire-energy which can be -sensed- by some beings. But are generally inaccessable and unable to be manipulated further. They are simply conserved as subatomic particles which eventually are recycled into different forms of life.
Another example would be when Xena simply breaths; or even when she isn't; her breath and her pores are giving off minute traces of Gaia energy and the energy of the phoenix inside of her. These particles are much less numerous than those left after a battle; like comparing the amount of sand that moves through an hourglass each second to the amount of sand in a dust storm honestly.
Energy particles differ in strength and potency depending on how they are originally manipulated. To which I will separate into three broad cateogries.
1) Unmanipulated energy.
2) Partial manipulation.
3) Complete manipulation.
Unmanipulated energy is the energy which is given off by the body; or which resides within the body; that is never used for anything that takes manipulation of it. The only way in which this energy is used is as "cellular energy" such as that which you regain by sleeping, eating, and other such activities.
This form of energy is the most saturated, and notable form of energy in the universe; making up the total of all individuals' bodily energy and their daily energy. However; it is also the least accessable by outside forces unless they have an ability which allows them to do so. Such as blood magic; or something which affects the inner workings of an individual's body.
In other words; this type of energy, while being the most powerful, is also the safest form of energy to have. Because it either resides in large doses within one's own body; or in minute doses outside the body once mostly used by the body itself.
Partially manipulated energy is energy which is used for small activities that are not part of large-scale manipulation. This can be achieved in a couple of ways which I shall break down as well.
One way to achieve this is a passive ability which heightens ones bodily functions; most normally their senses; but is something that does not come with their race.
For example: An air elemental having a heightened sense of hearing comes from the air currents passively carrying the sounds to their ear. This energy is only partially manipulated because it's something that requires so little effort that it barely even takes any energy at all; so it gives off almost nothing.
Another way to achieve this is to 'dabble' an ability into -another- ability.
For instance; ice manipulation. This is done by taking away heat from water while manipulating the water itself. The heat is; generally; taken inside oneself. This is two forms of energy as such. The majority of the energy being manipulated is water energy; the minority is thermal energy manipulation.
Partially manipulated energy gives off next to nothing in forms of usable energy. The energy that is used less is simply stored within the person's body most times; or if anything -is- given off, it's such a trace amount that even someone who manipulates energy would have a hard time manipulating it; because the most they could get out of the energy is what was done by the original user.
Completely manipulated energy is the most -noticeable- form of energy. This is the energy that is used as part of a large-scale manipulation. And energy that is consumed in large amounts as well.
This form of energy is -originally- unmanipulated energy that is resting within a person's body. All forms of energy start as unmanipulated energy actually. But with complete manipulation; the energy is taken from within and used in a notable way that preforms a very active ability.
One example of this is combat. Any and all forms of combat require large portions of energy to be consumed. Whether it be simple kinetic energy that is gained by the body consuming the potential energy within it, or something more complex like magical energy. It still requires energy.
Complete manipulation of one's energy is risky however. Unless the person is well-trained in perfectly conserving their own energy in each and every task that they perform; they are likely to use more energy than required in a combat-type situation, and that will give off wayward energy that is completely un-tampered with.
This free-flowing, wayward energy is almost identical to unmanipulated energy in that it's extremely potent and dangerous if someone learns to manipulate it or absorb it. It is extremely powerful and packed with the possibility to be formed into something else depending on the amount of energy that is 'wasted' by the original host of said energy.
Each of these types of energy all have the same energy signature as long as they come from the same person; but as is outlined, each one has it's strengths and draw-backs as well. You can do much more with manipulated energy, but it leaves the drawback that someone else might be able to use whatever is left once the original individual is finished with their 'task.'
If a person (or artifac such as the Staff of Magi) has an ability that allows them to manipulate wayward energy; then the more completely manipulated energy a person uses; the more wayward energy particles there are for said person or artifact to have at their disposal.