Watch the Locrian online guitar lesson by TrueFire from Rock Guitar Greatest Hits Vol. 1
Lesson Source: Robbie Calvo's Modal Expose
The A major scale from G# to G#
G# A B C# D E F# G# The bold letters are the chord tones and arpeggio tones of a G# diminished triad and a G# minor 7 (b5) chord.
We can apply the arpeggio in position over the chord backing track and hear how strong that sounds. It should be noted that a diminished chord and a minor 7 (b5) chord will never really sound resolved or consonant because it is dissonant by nature. These chords don't function as resolutions by nature so make sure you remember that and understand that they will sound tense unless resolved to another chord.
We can apply the A major scale played from G# to G# over the chord backing track and you will hear the tonality and tonal center to be that of the 7th note and chord. This G# is the locrian mode.