I do both. It all depends on distance to the target. If you only use a handle hold, you limit your self to the set distances that the rotation is right for that hold. If you do both you are able to stick at more distances.
A word of caution, be very careful with a blade hold on a sharp knife. It works, but you could easily remove a finger throwing a big knife.
For instance, the FBMLE (any FBM really) has enough blade height from spine to edge, that you can grip with less risk of finger slicing.
If you have any doubts, just stick with handle hold.
I have a couple video's of me throwing a FBMLE with both handle hold and blade hold.
However, I am gun shy about going to Photobucket to post them, because of all the virus issues with Photobucket right now.
Let me see if I can scare up those threads and link, or repost them here without going directly to photobucket.
here are some video's of me throwing my FBMLE, and other fun stuff.
This is at 25'
I'll see if I can find that blade hold. It's on here some where.
OOPS, that was the blade hold. Now maybe I will find the handle hold.