What is the role of confidence in the context of masculinity in Hemingway's A Farewell to Arms?

In A Farewell To Arms, Lieutenant Henry often operates under the belief that confidence and masculinity go hand in hand. Henry escapes being executed by the Italians through his own bravery and self-confidence.
Henry also takes particular notice of Dr. Valentini's mustache, his starred-uniform, and his status as a Major (all of which symbolize traditional masculinity), as well as his confidence in being able to operate properly. In contrast, the previous doctors who looked at Henry's leg lacked the confidence—and, thus, the masculinity—that Valentini had. They suggest waiting to operate, "three months, six months, probably" (96) but immediately highly recommend Valentini when Henry seems dissatisfied. They kiss Henry "delicately on the forehead" (98) and refuse a drink offered by Henry, (Valentini gladly accepts a drink). Hemingway's vision of A Farewell to Arms tightly intertwines masculinity and confidence; the confident surgeon possesses many traits of classical masculinity (his mustache, his status as a Major,  his appreciation for alcohol, and so on), while the more meek and unconfident surgeons do not.