Share prices rose Friday in a lackluster session on the London Stock Exchange. The Financial Times-Stock Exchange 100-share index rose 6.3 points, or 0.34 percent, to 1,858.4. Volume was 482.7 million shares, compared with the 593.5 million shares traded Thursday. Dealers said the market appeared to be resting after a fitful week of watching and waiting for an array of economic indicators. However, market analysts contended that the underlying tone of the market remained firm after Thursday's surprise narrowing of the British current account deficit to 560 million pounds, or $989 million, in September, less than half its August level. The Financial Times 30-share index rose 6.3 points to 1,508.9. The Financial Times 500-share index closed at 1,056.99, up 3.51.