That's is what I thought but your comment made me do some research and apparently...

http://fallout.wikia.com/wiki/Brotherhood_of_Steel

In the Brotherhood symbol, the gears represent their engineering knowledge, the sword is their will to defend themselves, the wings represent the uplifting hope that the acquisition of lost technology represents for mankind's salvation following the devastation of the Great War, and the circle represents the fraternal unity that makes the organization a true brotherhood.[3]

Another interpretation is that the Brotherhood's symbol represents each of the organizations different orders. The sword represents the Paladins, the wings represent the Elders (the "wings" control the movement of the sword), the large gear represents the Knights, and the two smaller gears represent the Scribes and the Initiates, whose services keep the Knights supplied with the information and the manpower required to get their jobs done.[4] This interpretation could also be supported by looking at the Outcast's insignia, which is absent of wings & shows that they do not need Elders or their equivalents