In article om,
Dave Liquorice wrote:

Hold the blade?

Yes. Fit the spanner on the nut so that there
is a slight angle between it and the blade, and
squeeze the two together.

I have a vague memory that Soddes Law says that
(for undoing) you have to fit the spanner angled
just behind the blunt edge and squeeze gripping
the sharp edge.

--
Tony Williams.