Spanish to English Law/Patents Law (general)

Hi,

I am translating a court report from Spanish to British English. The problem part is in a section which relates to circumstances that modify the criminal responsibility of defendants and the potential for mitigating circumstances to be applied. The defendant is trying to use his confession to get mitigating circumstances applied to him. Below is the section:

"Su actitud lo hace merecedor de la aplicación de la atenuante analógica de confesión del art. 21.7 del CP, alegada subsidiariamente por su defensa, si bien no como muy cualificada por no existir merito para ello."

My attempt so far is: "Thanks to his attitude, the basic mitigating circumstance of confession from art. 21.7 of the Penal Code should be applied to him, argued subsidiarily by his defence, although not as well classified as it was not required."

My main problem is that I'm not sure whether the "cualificada" in the Spanish text relates to "aplicación", "atenuante" or "confesión" and it's greatly affecting the way I translate the rest of the sentence. Can someone help please? Would "qualified" or "classified" (or something else) be a suitable translation for it? Thanks in advance.