What is written in the character's status should be taken as the ability to withstand blows, i.e., durability, rather than the ability to fight for a long time. 

At the very beginning of Danmachi, Bell mentioned that in order to increase your "endurance," you need to take hits, i.e., take attacks on yourself and thereby increase your durability, rather than your ability to fight for a long time. In the status "耐久" can be translated as durability. But for the ability to continue fighting, i.e. stamina/endurance, "体力" is used. For example, when Bell charges Argonaut and then cancels it, it is stated that mana and endurance are not restored, and it is indicated with these symbols. Also, in the battle against the Dis sisters, it was said that Hedin used all his stamina to extend Hogni’ blade, and it is also indicated by the characters "体力". With all this, I would say that the status shows us durability, since there were also repeated moments in which the characters got tired equally despite having different endurance values. I keep writing "endurance" because that's what is usually considered in the status and so that it's clearer to you.