Few Guardsmen ever advance to the rank of Gue'vesa'vre. Some will sadly die as mere Vesa'la, armed with little better than the weaponry the Imperium would throw them into the meat grinder with. Some will achieve the rank of Vesa'ui, Sergeants and vehicle drivers trusted with greater roles, who may die or choose to remain in their position, feeling they best serve the Greater Good in these roles.
It is a rare soldier who shows the commendable lethality and long service record who may attempt to ascend to the rank of Gue'vesa'vre. Such a path is not easy, as arguably out of a conservative spite against the Gue'la in general, members of the Fire Caste deliberately ensure the trials required to attain this role are difficult to the extreme. A Gue'vesa'vre will forsake his home and travel to the Inner Spheres, the core of the Tau Empire. Though many will journey to T'au itself, some will find themselves on still-reputable Septs such as Vior'la or Bork'an. It is here they supplement their existing knowledge with the grueling training regimen set out for them. They will become experts in a variety of Tau weaponry, from the humble Pulse Rifle to learning to pilot the fearsome Hammerhead. Those who adapt and excel in these roles are masters of a variety of weapons and ways of warfare.
The final barrier to acceptance is the Trial by Fire, which tests the mettle and devotion to the Greater Good of these soldiers. Many will adapt to this adversity and excel, as humans are wont to do. Indeed, while some Fire Caste members are optimistic about the military potential of the rapidly expanding swathe of Gue'la worlds falling under the Tau's influence, a few voice words of concern that the Gue'la armed forces may one day outnumber - and dare they say it, outfight - the Tau in their own Empire. Such naysayers are a minority, however, as the training regimen of the Gue'vesa'vre ensures a fully compliant servant of the Greater Good at the end of it.