User blog comment:B214/Question and Answers 2/@comment-4547267-20140604230500/@comment-24866657-20140605092751

@jopjopjop

Right, and Siegfried has Twice Critical and he does not have any gauntlet. In the end it's either the names come from the user or how they call the sacred gear based on its appearance, who was the one named all sacred gear anyway, God of the Bible? The sacred gear reaches to the user's desire, Siegfried wanted more arms and he got it, if Issei's arm got cut off then Boosted Gear would give him an armored one or something else, and it's not like he couldn't use Boosted Gear anymore if his arms got cut off. As showed in Juggernaut Drive the armor was capable of growing more dragon arms because the user wanted to stop his enemy.