Out of the swirling mists of bureaucratic war there has emerged a clear victor in the struggle for preeminence in foreign policy. Secretary of State Cyrus Vance - not the widely publicized national security adviser, Zbigniew Brzezinski - has come out on top.

Still it remains a question whether Vance can assert himself for long as the undisputed master of foreign policy under President Carter. For it is not clear that he has the personal qualities to be a strong secretary of state.

Vance is well known to be a highly competent and widely experienced official, straightforward, honest, clear thinking and articulate. He has a firm grasp on most international problems, and he understands their interplay with American domestic politics.

It has been said against him that he is a mere problem-solver, without a world historical philosophy. He does believe in the slow, patient address to areas of tension; he chips away at problems and makes progress by slogging through. That may not be as flashy as the "big think" abstractions fashionable in some quarters. But it is a philosophy, and one that happens to suit a time when little else besides patient slogging can work.

Most important of all, Vance gets on with practically everybody. He commands the support of President Carter and of all the president's chief aides: Vice President Mondale, Hamilton Jordan and Robert Strauss. He has the confidence of both the disarmers under Paul Warnke and the Pentagon under Harold Brown. The Congress likes him, and so does the diplomatic community.

Indeed, this overwhelming support ensured that he would eventually hold off the challenge of Brzezinski. For Brzezinski, apart from president and Mrs. Carter, can probably count no more than five supporters in all of Washington.

Some of the traits that have earned Vance such widespread approval, however, complicate his present task. He does not assert himself in ways that give other people a hard time - particularly other people in power. On the contrary, he is used - as a lawyer serving clients and as No. 2 man in government to such strong leaders as Robert McNamara at the Pentagon and Averell Harriman in the Vietnam peace talks - to making accomodations with the boss.

As secretary of state he has been far too deferential to the mere notions of the president. He approved against his better judgment an overemphasis on human rights and an initial arms proposal to Russia that undid all past negotiations.

He has repeatedly gone off on futile trips merely because the president pledged he would go. Thus he visited Africa a couple of months ago on an abortive mission that was beneath his dignity in the first place - a mission to decide which among several black leaders would agree to accept the flag of surrender being waved by Rhodesia's white leader, Ian Smith.

In keeping with that deference is a distaste for bureaucratic politicking, Vance can get his pound of flesh when he wants to. He once extracted a hand-written note of apology from a White House aide who seemed to be circulating rumors that the secretary of state would have to retire soon because of ill health.

But Vance rarely asserts that power in his own behalf, and never for the sake of his department. Lesser officials at State, on issues that the secretary is not handling personally, have to do everything through the National Security Council. Not a few mistakes - including the blunder of supporting Somalia in its losing war against Ethiopia - could have been avoided if State had now the kind of authority it used to have under John Foster Dulles and Dean Acheson.

One reason Vance is so little prone to take charge lies in his post-Vietnam experience. As a leading - perhaps the leading - lawyer in New York, he lived at the center of an establishment that had lost confidence. He came to believe in a certain American guilt - for the condition of the blacks, for the plight of the Palestinians and, of course, for aggressive actions all over the Third World.

Those themes persist in his approaches to such problems as the Middle East, Africa, Southeast Asia and Latin America. They make Vance a patsy for the hard-liners, and complicate more than necessary his central aim of working out areas of agreement with the Soviet Union.

None of the weaknesses I have cited are insuperable. The administration's confidence in the secretary of state, now so visible, ought to foster more self-confidence. He can go on to become a distinguished secretary. But achieving that goal depends more upon himself than upon his stars.