This is a measure of your strength of will, your psychic power, your magical aptitude, and your spiritual power. High psyche people draw others to them, even if they don't want to, and tend to dominate social situations, whether by charisma or by sheer force of personality.
Psyche is often used to determine how well your powers work and how much control you have over them. It's also used in psychic combat, when minds struggle directly. It can be intended to cause mental damage or alternately to invade people's minds, stealing their secrets or controlling them. Psychic combat can be initiated by either touching your opponent, establishing eye contact, by magic, or by Trump contact. There are other means, but these are the most common. (For example, in some shadows, you can communicate mind to mind with ease while in different cities or even continents)
In this Amber, Fuyutsuki, Touga, Anthy, and Mutsumi are the Psychic Masters.
Finesse covers psychic stealth and psychic sensitivity. With sufficient Finesse advantage, you can slowly, subtly work your way into someone's mind and eat away at the foundations of their mind without them noticing it. The more changes you are making, the harder this gets and the more time it requires. If your Finesse is not greater than their Psychic Strength, it may take an incredibly long time, or even be impossible to make any deep changes in this manner. People with high Psychic Finesse detect efforts made to invade their mind and pick up on the use of powers around them more easily.
Finesse has the upper hand in psychic conflicts which are about fine control. If you are trying to manipulate probabilities to make a red-headed lust vixen who is hot for your body wander by, while someone else tries to make the lust vixen homocidal towards people who look like you, this is going to be a finesse conflict. If you are trying to read someone's surface thoughts or mess with their perceptions, then Finesse is going to be the crucial stat. If you want to try to manipulate 16 Logrus tendrils at once or use your Elemental powers to mold snow into a copy of Michaelangelo's David, then this is the important sub-stat.
A person with sufficient Finesse advantage can try to avoid letting other people bring their Psychic Strength fully to bear on their minds. They can try to fight a foe by 'nickel and diming' them to death. This may take a long time, turning the battle into a Mental Endurance contest, depending on the relative ranking of the various stats involved.
High amounts of Psychic Strength gives you additional oomph for your powers. Your magic is harder to dispel, your trump calls are harder to block, your trump gates are bigger, your Logrus manipulations last longer, and so on.
Some Psychic activities require brute force more than they do fine control. Things like changing the world laws, forcing trump contact, and simply diving into someone's mind to try to completely rewrite them from the ground up in a quick, sloppy manner, are handled by Psychic Strength.
While someone with Finesse can try to hold a high PS person at a mental distance, if you beat them in Psychic Strength and their Finesse doesn't beat your PS too horribly, you may be able to simply batter their defenses aside and dive on in, while taking some mental blows on the way in.
Your Psychic Strength buffers your Mental Endurance in psychic conflict, as if it was armor. It also determines how hard your Psychic blows hit.
Psychic Strength also covers your charisma and general strength of will. The more you have, the more effectively you can simply browbeat people into doing your will and avoid being browbeaten.
Some examples of powers where Finesse is more important:
Some examples of powers where Psychic Strength is more important:
In some cases, neither stat is more important because the power requires a lot of both to be safe (such as Mind-Shifting) or effective or because the power can be used both for brute force and for fine manipulations.