Anyway, Defence against a Cross-Wrist Grab sounds like some kind of Harry Potter lesson!
Actually, when I first read it I thought you'd said Defence agains a cross -wrist crab, which had me confused for a while. On a more serious note, that sounds like a useful lesson. I can imagine that sort of unexpected move could be very difficult to counteract unless you knew what you were doing...PS my reference to the scary underwear was in no way meant to illustrate anything other than the defiance I was feeling against my advanced age. Sort of along the lines of
When I am an old woman I shall wear purple
With a red hat which doesn't go, and doesn't suit me.
And I shall spend my pension on brandy and summer gloves
And satin sandals, and say we've no money for butter.
I shall sit down on the pavement when I'm tired
And gobble up samples in shops and press alarm bells
And run my stick along the public railings
And make up for the sobriety of my youth.
I shall go out in my slippers in the rain
And pick flowers in other people's gardens
And learn to spit.
You can wear terrible shirts and grow more fat
And eat three pounds of sausages at a go
Or only bread and pickle for a week
And hoard pens and pencils and beermats and things in boxes.
But now we must have clothes that keep us dry
And pay our rent and not swear in the street
And set a good example for the children.
We must have friends to dinner and read the papers.
But maybe I ought to practice a little now?
So people who know me are not too shocked and surprised
When suddenly I am old, and start to wear purple.
To this day I have no idea how I did that. 
