Second, there is a growing sense that extremist jihadist forces are beginning to eclipse the rest of the opposition with better weapons and fighters. But outside powers have been reluctant to provide much-demanded antiaircraft and antitank missiles until they are assured that the arsenal will not fall into the wrong hands if the rebels achieve their goal of toppling the government of President Bashar al-Assad.

Third, rebel commanders said they were facing a stark new reality. Their advances in recent weeks have been built largely on fatigue and low morale among government soldiers, as well as on random weapons captured from military bases, they said.

But both the initial attempt to batter the ramparts of Damascus and the long struggle for Aleppo have given many commanders the sober sense that they had better obtain stronger weapons for any final showdown over the main government strongholds.

The meeting here concluded with twin promises between the commanders and their outside supporters. In exchange for unification, the main backers of the rebels said they would funnel money and weapons through the new military council rather than playing favorites among the groups, commanders said.

“Before, they were always trying to bring different factions to their side, they created divisions, but now they are helping to create unity,” said Gen. Abed Farzat, a military commander from Aleppo.

The pivotal countries present were Qatar — which provides most of the financing for coalition efforts — Saudi Arabia, the United Arab Emirates, Jordan and Turkey, commanders said. Those countries are still likely to support their own favorites in the game of regional influence, but the main effort will be concentrated on the new leadership, analysts said. Britain and France also sent representatives.

The commanders present agreed to the formation of an internal leadership, led by the new chief of staff chosen here, General Idriss. The general, described by commanders as a former professor at Syria’s war college, had previously tried to link external and internal opposition efforts.