With the nomination of a woman to the United States Supreme Court, President Reagan has broken a historic precedent and made a move that should go far in bolstering women’s support for his administration. Reagan urged the Senate to give “swift bipartisan confirmation” to Sandra Day 0’Connor, 51, ,a judge on the Arizona Court of Appeals since 1979. Assuming she receives Senate confirmation to fill the vacancy created by Justice Potter Stewart’s retirement, Mrs. 0’Connor will become the 102nd justice, after 101 male appointments in the court’s 191-year history. Women have held cabinet positions, served in the House and Senate, and as state governors. They have held many judgeships but never a justiceship of the Supreme Court. Her nomination fulfills a campaign pledge made by Reagan that one of his first appointments to the court would be a woman. Indeed the nomination amounts to an important first step in pulling many disaffected Republican women back to the Reagan corner, Some women’s groups have been critical of the president for failing to appoint what they consider sufficient numbers from their ranks to important posts in government. Calling the appointment the “most. awesome” within his power. Reagan described Mrs. O’Connor as being “a person for all seasons.” Some conservative and far right opposition has been indicated over her reported support, as a, state senator several years ago, for a measure legalizing abortion and for another which would have submitted the Equal Rights Amendment to Arizona’s voters, But a White House spokesman said she had told the president she “is personally opposed to abortion and that she feels the subject of regulation of abortion is a legitimate one for the legislative area.” A Phoenix political editor said she “does not have an image as being a drumbeater for ERA or abortion” Unless the Senate finds adequate reason to question Mrs. 0’Connor’s ap pointment, it appears the president has found a nominee who will appeal to a wide range of constituency: A respected woman who apparently advocates women’s rights without feeling a need to crusade on the issue, and a basically conservative jurist committed to interpreting and implementing the law.