Re: Hand Forms
Here's what I think about hand forms. I would say that the shape of the hands during the technical application of techniques is what is being referred to here. Does this mean that someone with out hands can't do Aikido? I don't think so, but it does mean that some options won't be available to them, such as doing the grab necessary for go-kyo, or catching uke's arm in techniques such as kaiten-nage. Hand forms certainly isn't considered traditional Aikido, but maybe its just a new take on something that's been there all along. If one looks at photographs of the Aikido masters, then it is clear that their hands do seem to form certain shapes during techniques.
I view this study of hand forms as something extra rather than something necessary for Aikido practice. However, they are not useless. Considering the outside is just as important as considering the inside. We live in the world of forms, and without them, reality would cease to exist as we know it. Try waving hello to someone with a closed fist, or with just the middle finger pointing up, and everything changes.To me, hand forms come about as a result of proper technique, much in the same way the proper technique comes to form as a result of the application of principle. So, it may be more of a side-effect, then a conscious effort in application.
What are some uses of hand forms? They can be used for taking out the slack in a technique, maintaining points of contact, creating points of contact, atemi, catching uke, leading, and extending ki. For me, I think it is important that they occur naturally. One should not should take any time at all to get a proper hand form, especially with grabs (which is why i try to avoid grabbing uke as much as possible).
Any other ideas for the uses of hand forms?
In considering my own practice, in response to the OP's question, here are some of my own ideas of hand forms and their application in technique. These forms don't include positions, only shapes. For example, the te-gatana can be positioned palm-up or down, or sideways.
Te-gatana- sumi otoshi
C-shape- Catching uke's arm in kaiten-nage
The cat's paw(TM)- Floating uke
The sprocket hand (TM)- Taking out slack/extending ki
The Limp wrist- Yokomen applications
Open palm- Atemi/deflection
Closed fist- Atemi
One finger out grab- 4kyo
The spear- Irimi nage
Feathered fingers shining the ball-Round movements
One thumb out grab- Shiho-nage lock
Rolling thumb to the outside (open palm) -Ten-chi nage