What is the meaning of Tempered?

Having a specified disposition or temper.

Pertaining to the metallurgical process for finishing metals.

Pertaining to the industrial process for toughening glass, or to such toughened glass.

Moderated or balanced by other considerations.

Pertaining to the well-tempered scale, where the twelve notes per octave of the standard keyboard are tuned in such a way that it is possible to play music in any major or minor key and it will not sound perceptibly out of tune.

simple past and past participle of temper

Source: wiktionary.org