"To be perfectly honest with you," said Walter F.Mondale, "I'd just as soon not be catapluted off this thing."

The remark was made to a mob of photographers, pressing the new Vice President periously close to the edge of a balcony off his room in the Hotel Crillon overlooking the Place Vendome in Paris.

But it might well have applied to the entire jorney Mondale has undertaken on behalf of the new administration. Only 69 hours in office, with limited experience in foreign affiars, Mondale was dispatched by President Carter last Sunday on a high-level diplomatic mission to six Europian countries and Japan.

It was the equivalent of teaching a youngster to swim by tossing him off the dock. But the boy from Elmore, Minn., has not drowned; in fact, he has managed rather well.

Mondale, arrived here at 7:30 a.m. Washington time, after a 19 1/2-hour flight from Paris, broken only by a pair of refueling stops in Keflavik, Iceland , and Anchorage, Alaska. He slept through the second stop and arrived looking not much worse than when he had left Paris. He will begin talks with Japanese officials.

The Vice President had told a reporter - who had actually inquired in French about Soviet strength in Europe - that he appreciated being asked, "How can I look so handsome and vital after this long trip?" When the laughter at the press conference subsided, Mondale said: "It's the nobility of my ideals that shines through . . . that's your lead for tomorrow."

The ability to kid himself publicly after a week in which he had gone head-to-head with the likes of West Germen Chancellor Helmut Schmidt, Italian Premier Mario Andreotti, British Prime Minister james Callaghan and French President Valery Giscard d'Estaing - to say nothing of Haig - was perhaps the best measure Pope Paul V1 and Gen. Alenanderof Mondale's own growing sense of self-confidence.

There had been no such ease in his first meeting with an international press corps in Brussels five days earlier, at the end of his first day of negotiations. Facing 150 reporters from more than a dozen nations, Mondale was frowning and unusually slow-spoken - as if concentrating furiously against the risk of a single misstatement.

He had flown to Brussels from Washington on Air Force Two - the Henry A. Kissinger "shuttle diplomacy" special. He did his best to look relaxed and at home in the "Kissinger cabin," receiving reporters in an opennecked business shirt, with an old flannel sport shirt thrown over it. He told them, "I feel ready."

But as his press secretary, Albert Elsele, later told reporters: "There was a great deal of uncertainty in his own mind beforehand . . . he didn't know what to expect. It was a new atmosphere, a new experence."

But Mondale got through the first press conference and the day's meetings with Belgian, Dutch, NATO and Common Market officials without a fluff, impressing not only foreign officials but apparently even Gen. Haig, who was described as watching Mondale with unusual intensity.

Afterward, Eisele said, "He was very tired and a little exhilerated. He felt much more confident when he left Brussels."

Although reporters had to rely on second-hand accounts of Mondale's conduct in the private negotiating sessions, evidence of his growing self-assurance could be seen in the increasing number of personal grace notes that lightened his public moments.

He grinned unselfconsciously as an Italian translator embellished his own rather plain remarks with trilling cas cades of liquid-sounding verbiage. He joshed Jim Callaghan and joined him in singing labor ballads at a boiserous dinner. He told the proud French he felt right at home in Paris because he had walked for years on Nicollete and Hennepin Avenues in Minneapolis - giving those streets their flat Midwest pronunciation.

He invited the Paris press corps for cocktails, then made them pay for their own drinks, explaining that the austerity policy of the Carter administration extended to his travel budget. He even surviced the embarrasment of confessing to the Pope that he had left on his plane the autographed copy of the inaugural address that Carter had asked him to deliver.

Increasingly, too, he asserted command of his own entourage of economic and foreign policy experts. One official, who had been notably uninformative at his briefings, began to open up a bit after Mondale kidded him about "leaking" everything he knew to the press. Another, who had been sarcastic toward both Mondale and reporters, was firmly reminded that he was no longer instructing ivy league undergraduates.

Substantively, the trip is more difficult to evaluate. At the end of his week in Europe, Mondale pronounced his mission "a success", adding, "we are now on a solid basis for progress."

Most European and American diplomats seemed to agree. A German officials, noting that it was hard for the methodical politicians of his country to understand the sudden emergence of two such "unknowns" as Jimmy Carter and Walter Mondale, said he was reassured to find the new Vice President "a man of weight".

The need for the kind of reassurance was heightened, rather than lessened, by the President's own actions during the past week. His statements on the abolition of nuclear testing and the reduction of nuclear weapons stirred serious apprehension in the capitals Mondale was visiting.

"Quite frankly", said one Mondale aide, "the question has come up about what would deter massive Soviet conventional power in the absence of nuclear weapons."

Mondale did his best to reinterpret the President's remarks in a way that reaffirmed, rather than weakened, the American commitment to NATO's nuclear deterrent.

The need to counter the growing Soviet military strength in Central Europe became a larger theme of Mondale's talks than was originally planned; he may well return to Washington as a strong advocate of giving NATO high priority in the administrations current revision of the Ford defense budget.

But on the basis of present knowledge, Mondal was less than totally persuasive in gaining reciprocal commitments from many of the leaders he met.

West German newspapers reported after his visit to Bonn that Schmidt's government would stand by its previous economic plan - regarded as in adequately expansionist by Carter administration officials - rather that heed Mondale's urging to "reflate" faster to help weaker countries overcome their export slump an dunemployment.

In Paris, Giscard plainly indicated his displeasure at the Carter-Mondale drive to convert his cherished "economic summit" into a broader meeting of top officials, tackling nuclear proliferation and other ticklish political issues as well.

More important than these reviews is the one Mondale gets from the White House. As his aides candidly acknowledged, the trip is another of the tests Carter has given his running-mate as part of the process of moving him into a central place in the President's own entourage.

A discernible shudder went through the entourage when, after two days of big Mondale headlings back home, Carter was overheard by reporters at the White House telling Sir Peter Ramsbotham, the British ambassador: "Fritz won't want to come home. He's having such a good time and getting so much attention."

A long-time Washington traveling with Mondale told Eisele: "If Lyndon Johnson had said that, you'd known you might as well not go home".

But the atmosphere lightened a few days later when Jody Powell said Carter found the diplomatic response to Mondale's trip "very encouraging" and praised the Vice President's "substantive" work.

With that degree of encouragement, Mondale is flying home Tuesday.