Peter Seth

Wrist grasps are to initiate beginners into the concepts of circularity. But if/when you become more aware of concepts you can pre-empt attacks and actually get your attacker to grasp your wrist/elbow/shoulder etc etc by presenting whichever one to him before he has formed his attack.
As he is thinking about attacking you, feign an attack on him, eg: uraken (backfist strike) to the face. If you are in the right position he will automatically raise his arm/hand to defend and most likely grasp what is offered. - and there you go!
This is very simplistic as an example but try it.

With more experience you will become aware that 'techniques' are just a finish to a movement, as a full stop (period) at the end of a sentence. Real 'aiki' is being in the right place (where your attacker does not want you to be), with good 'form', moving in an appropriate direction which will initiate blending and flow, to lead, control and dissipate his energy.

To be a little more frank, when you fight or struggle to apply a technique (with an 'I must apply this/that/a technique' mind), it can sometimes be viewed as 'backup to a b*lls up', with regard to real 'aiki' concepts.

Its a long and wonderful learning curve, which like all curves leads back to the source so don't be in too much of a hurry enjoy the journey.
P.