Brotherhood T-45d power armor provides a Damage Threshold of 22 as well as a bonus of 10% to Radiation Resistance, +2 to Strength and a -2 penalty to Agility. It is not quite as protective as T-51b power armor or its variants, nor is it as protective as Remnants power armor, but it still provides protection superior to every other form of non-powered armor in the game.
As the name indicates, Brotherhood T-45d power armor is the Brotherhood of Steel-specific variant of the T-45d power armor. In addition to its other properties, the armor serves as a disguise, allowing the Courier to appear as a member of the Brotherhood of Steel. It is otherwise identical to the standard T-45d power armor.
Dead Wind Cavern - this armor can be obtained near the legendary deathclaw. There is a dead Brotherhood of Steel member in a corner, clad in Brotherhood T-45d power armor. This is also the same area where the unique weapon Mercy is located.
Brotherhood of Steelpaladins rarely wear Brotherhood T-45d power armor. This is because a key list, which indicates it is meant to hold Brotherhood T-45d power armor, is instead composed of Brotherhood T-51b power armor. This also results in armored Brotherhood members occasionally wearing T-51b armor with T-45d power helmets. [verified]