Well, I got too impatient last night to wait on any advice, so I went ahead and up'd the black hades. It went from 984 def to 1500 def, so I was pleased with that... but not so pleased when I found out the str requirements for shadowplate was 230... too high for my merc (188). Thank goodness for the 3 sockets, otherwise I would've freaked!

Anyways, one -15% requirements jewel, 2 P amythists (one in a socketed helm just to put it on, and one in the armor just to be able to keep it on), and 1 sol rune (damage reduced was the best final mod I could think of for the armor, since 1 P topaz really wouldn't make much diff) later, and my merc is now finally wearing his black hades shadow armor. Lesson learned!