Everything you just said indicates weak if you are a righty, except it got weaker with feathers, which it should not do, and the paper test showed stiff to begin with. If you added feathers and it hit right, it might have been a bit stiff to begin with and you made that worse with feathers by creating additional contact. You said paper tuning showed stiff, so maybe the full length bare shaft was an accident, or something happened you could not see and all your mistakes combined to put it in the middle, even though it was stiff. Bare shafting is tricky unless you have nearly perfect form, every single shot. You almost need a clicker. Paper will show you what the arrow is doing right out of the bow. If the arrows are actually stiff, they might be making contact and kicking, which might seem to be weak but is not. If the arrow is actually weak, then dropping considerable point weight should make it show stiffer bare shaft. If it actually makes it show weaker, you are probably getting a false reading from contact. Try putting enough tip weight on to get a correct tear through paper (which you said was stiff, so more weight), then re-do the bare shaft test and see what you get. That would at least give you some idea of what is not going on.