Like Yhwach, you have been born with the innate ability to distribute a piece of your soul to another by being touched by them (with no major loss to yourself), allowing you, like Yhwach, to acquire power by bestowing an ability. This enables those "gifted" to cultivate it and then taking it back. This ability can be broadly broken into a few sections, but it isn't all it can do, though that's for you to discover.
In the distribution of your soul, you can heal wounds that one's soul could not heal alone. This includes physical, mental, and spiritual ailments of those who have touched you. While the person's wound is healed, all of their knowledge, skills, and talents will be engraved inside the piece of soul they received from you. The price for this healing is a drastic reduction in the person's lifespan, and once the person has died, the augmented fragment will return to you with all of their knowledge, stats, skills, and talents. By having others drink your blood within a ritual, you may distribute your soul fragments in a much more powerful way by engraving a letter signifying an ability directly onto another's soul. You can forcibly retake these soul fragments at any time through "Auswählen," which allows you to absorb the energy from those you have gifted power to and send it to those who need it, or you can take their powers for yourself. Those taken from will perish, while those on the receiving end are revitalized with greater strength than they possessed before.
Upon activation of this ability, the targets are engulfed in massive columns of light. Dodging this light will not protect someone from having their power taken. The Auswählen can be used to revive those you have "gifted" power by stealing the powers and life of others. The greatest use of this ability is the Sankt Altar: you summon five orbs of energy in the air around a target that shoot out concentrated beams of energy at the target, forming the pattern of a large Quincy Zeichen. These beams rob the power of their target and transfer it to you.
However, beware that the use of this ability temporarily forms a piece of Still Silver within the hearts of those you have targeted with Auswählen. If this is extracted at the proper time and forced into contact with your blood, you will briefly lose access to your powers (seconds to a full minute).
The last ability is Reiatsu Infusion, which allows you to transfer your Reiatsu to others through contact with an object that you have infused with your Reiatsu. This temporarily forces an individual gifted with your power to act as you wish.
Remember, these are just the broad strokes of what this ability allows you to do. So, study and practice, and you may discover more.