UPDATE 1-CANADA STOCKS-TSX set for 1 pct weekly fall on broad slip

* TSX down 79.91 points, or 0.52 percent, at 15,384.51 * All but one of the 10 main sectors were in the red (Adds details) By Alastair Sharp TORONTO, Sept 19 (Reuters) - Canada's main stock index slipped on Friday and headed toward a 1 percent decline for the week, with heavyweight resource and financial stocks notching moderate declines. While energy stocks have weighed all week, TransCanada Corp bucked the trend, rising sharply for a second day after it said its existing set