As so happens to all traditional Salubri, his birth name was not Gabriel but this was the angelic name he received after the Blooding.
According to the Salubri historian Nuriel, the five Salubri progenitors of the Warrior caste were Uriel, Za'aphiel, Ezrael, Aariel, and Gabriel. However, this tale does not mention Ithuriel. Besides, according to Qawiyya el-Ghaduba account, she was the last childe and bearer of the first-hand copy of the Code of Samiel, penned by the mythical Warrior himself centuries ago. If that is correct she would be Samiel's favorite childe who single-handedly launched a divergent Warrior's path from within the clan of healers.
Note that at least one other Salubri also bears the name Gabriel, a seventh-generation grandchilde of Ithuriel.