The hand is the most frequently symbolized part of the human body. It gives blessing, it is expressive. According to Aristotle, the hand is the "tool of tools." In general it is strength, power and protection. However, it can just as easily mean generosity, hospitality and stability; "lend a hand". It is used in gestures of greeting and friendship (shake hands).
The right and left have different symbols related to each: right - the rational, conscious and logical, as well as aggressive and axious, left - opposite of the right, weakness, decay, death. However, the two can be juxtaposed to symbolize balance and the middle (The Left Hand of Darkness, LeGuin, its reference to the Tao, See YINANDYANG).
Hand gestures vary in symbol: laying hands on something - blessing, consecration, transference of guilt, healing; raising one's hand - to swear, honesty; hand on heart - love, adoration, salutation; two hands clasped - peace, alliance, friendship; hands at side - negligence, arrogance (on hips); with water - purification, cleanliness, innocence.
http://umich.edu/~umfandsf/symbolismproject/symbolism.html/H/hand.html
- Adaptability - because the hand is the "tool of tools"
- Rescue - because of a "helping hand" and a hand pulling one out of a pit