All I can say is that the RNG Gods favored him. I ran MC a few times this last month with him (solo) when I was bored.
So I ran MC last night, Monday, before raid reset – Bam – Garr dropped the Right Half of Thunderaan’s Eternal Prison. Tuesday came along today and I ran through it again (after I did on my warlock first of course) and – Bam – Baron drops the other half.
So I took the MATs I have saved for my Warlock (when the other half drops for him) and made the sword on my DK!
I’ll still be running MC weekly on the warlock til he gets it complete too!