Giving Reiki sessions to the dying and grieving is a way of easing the fear and hurt associated with end of life.
The only differences between a normal session and a palliative one is that you may have to do it without hands-on, depending on pain levels, and the setting of your intention. Obviously setting an intention for healing may not be for the clients highest good. Intentions are usually that they are free from pain and fear, and that they feel warm, loved and secure as they come to the end. Ask the Holy Spirit and the ArchAngels to surround them with comfort, love, peace and to carry them to the light. Use whatever belief system you or the client are most comfortable with.
Giving Reiki to someone as they end their journey, is really one of the most beautiful experiences. There is nothing to fear, as Reiki is a very loving, gentle and self-guided energy. Always remember the first rule of Reiki: Reiki can do no harm. That includes both the giver and the receiver.