Use me for example, of a sample of about 5 matches per weapon (not really that large but work with me) I average 2.3 k/d and a high of 23.0 with the thorn. Using the messenger I averaged about 2.0 with a high of 14.33. Multi tool, I average 1.8 with a high around 7.33. (my overall k/d is only 1.65 so you can see other weapons just do poorly lol) From playing with many weapons, I do believe that the thorn is cheap, though it only is really a problem for me in trials (which I have yet to go flawless on due to lack of competent teammates, thorn spam and lagggggg). To answer your question though, In my opinion, the best way to nerf the thorn would be to reduce its fire rate and range.