The Wagtail had a one pass tool years ago , it was called the combi, I still have two of them and they're worth their weight in gold. The original combi had a bit of a design flaw which I found a fix for, I think it was on account of that that they stopped making it.
When they made the original they had it so that you could swing the blade out of the way if you wanted to give dirty glass a good scrubbing, and this is what caused the problem, what they had not realised was that we never used that facility anyway, we could give the glass an extra scrub if needed, by simply pushing the handle down towards the glass and lifting the blade clear that way.
I did post a picture of it on here once, but I'm not going to sort through 3000 posts to find it.