I can confirm that Wiessner's route L'Imperiale on Mt. King in Val David, Quebec is a very hard and serious route. Back in the mid-'70s Al Long and I seemed to be climbing pretty well during a visit to the Val David climbing areas but were stopped cold by L'Imperiale---couldn't even see what to do, though had little trouble with the supposedly harder "Direct" put up by Turner or one of his compatriots a decade or so later. Though Canadian John Brett was apparantly the first to climb on the Val David crags, it was Wiessner's subsequent visits that really began the development of the area and of rock climbing in general in Quebec.
Fritz and I went out to Stoney Point on what I remember as being his first Stoney Point experience - in the mid-70s. He wanted to climb some friction - some face climbing, but nothing to exposed. I took him took to Spencer Slab - he loved it.
I'm not sure if any one saw the mountain profile of K2 in a couple recent issues of Alpinist. They go into good detail about Weissner's near successful climb in 1932 (right year?). Thinking that the Bottleneck was not safe, he cramponed up the rock next to it, which no one else has even attempted. Absolutely hard core stuff. One just shakes one's head in wonder.
I wrote a short paper on Weisner's ascent of K2 in college. I still cannot think of a more impressive ascent in mountaineering history. technically not a success I suppose and sadly there were men of much lower ability and perhaps character involved who created problems and ridiculous controversy regarding Weisner's actions.