Who to rank up

Poofinger250

I am 20k in teir 5 bascic away from rank 5ing Blade. I currently have 8 t2 alpha but I do not really get these very quickly. Here is the question. I just pulled a 5 star Corvus 2 days ago! Do I rank 4 him and use up my T2 alpha or hold off and r5 Blade in about a month or so. I am really stuck on this one. Neither awakened yet but 75% complete on act 5 so I will get a generic awakening gem and a class one still.