Beirut — The best thing, from Yasser Arafat's point of view, would be for the Israelis to open fire on him with everything they've got - and miss. The main danger facing the Palestinian leader as he maneuvers for the least distasteful possible exit from siege in the north Lebanese city of Tripoli may not be physical, but political.
There is, to be sure, ample physical threat to the man who, in the past 15 years, has come to symbolize the Palestinians to the world outside. Before a cease-fire that began roughly two weeks ago, he was under fire by Syrian-backed rivals who considerably outgunned him. They are still in place.
Before dawn Friday, as contacts went ahead on a negotiated evacuation of Arafat and his followers, Israeli gunboats offshore briefly opened fire on his positions. The boats, too, are presumably still there.
Yet Mr. Arafat seems concerned, above all, with the political danger of becoming an international irrelevancy - a future he knows would suit a number of prime actors in the Middle East arena, particularly Syria and Israel. The Americans wouldn't mind much either.
Signs of Arafat's concern are much in evidence around his headquarters in Tripoli, a mile or so in from the Mediterranean port area where Arab mediators hope he'll soon embark for other shores.
Time was, a few years back, when the stubble-bearded guerrilla chief was a rather hard man for the foreign press to get to. As he bid for world recognition in the late 1970s, that changed a bit. But rarely, before Tripoli, has he been so assertively available. Almost every day now, he holds a news conference - in spite of, maybe because of, the frequent absence of any fresh, substantive developments over the past fortnight.
His spokesmen, on the heels of the cease-fire, were telling just about all comers ''the chairman'' would not be averse to an interview.
In other ways, too, the PLO chief is visibly striving to conserve his hard-won recognition by friend and foe alike as an important force in Mideast politics.
Only incidentally out of safety considerations, Arab political analysts are convinced, did he seek permission to fly the United Nations flag on the Greek ships that are to evacuate his forces. He is saying, in effect: ''I remain, for the world, the unchallenged leader of the Palestinian cause.''
And when Arafat's Syrian-allied rivals, on Damascus's directive, stopped shooting late last month, Arafat moved quickly to fill the vacuum in foreign news interest with ominous predictions that his foes were preparing an imminent killer blow all the same.
Similarly, Arafat spokesmen grabbed headlines anew - and afforded Israel an excellent rationale for Friday's pre-dawn shelling - by claiming responsibility for a bomb blast Dec. 6 on a Jerusalem city bus. Saturday morning, Arafat officials charged - apparently without foundation - that Israeli boats had shelled Tripoli for a second night running.
The ultimate means by which Arafat hopes to combat the threat of reduced stature once out of Tripoli, some Arab analysts suspect, may be simply to stay put in Tripoli for longer than expected.
As waiting on that score continued, speculation focused on whether Israeli gunboats might try to keep Arafat from leaving if and when he makes the move.
The men who have dominated Israeli politics since 1977 - former Prime Minister Menachem Begin, present Prime Minister Yitzhak Shamir, and defrocked ex-Defense Minister Ariel Sharon - have never made any secret that they think they'd be better off without Arafat. Mr. Sharon, not one to mince words, has gone so far as to say Arafat should not leave Tripoli alive.
But at least so far, Mr. Shamir has avoided publicly encouraging such talk - maybe partly because the mechanics of a move against Arafat could be daunting if , as seems possible, he is afforded some kind of Western protection on his way out.
Some diplomats suspect Shamir may also have concluded that any advantage to Israel from such a move could be outweighed by the opprobrium Israel would face abroad, not least of all from a Reagan administration with whom Shamir has recently forged closer ties.