Bingley: SOED, in addition to the tool to which you are referring, also has 'piercing, penetrating' (as of eyes) and a 20th century cocktail (which sounds most unlikely in the circumstances!). Perhaps there's a link with umbrellas here (or screwdrivers -- in the drinks department). An Australian journalist, Keith Dunstan, wrote a book called 'Wowsers' a few years ago. If I can find a copy I'll let you know.