Deadpool, Vol. 2 #2 (1997)

Operation: Rescue Weasel That Wacky Doctor's Game!
While Deadpool is peeping in on Siryn, a band of ninjas is capturing Weasel; Deadpool tracks down his buddy which brings him to a compound in the Nevada desert where Taskmaster is training his pupils. Being quickly taken down by Taskmaster, Pool discovers that the bad guy has offered Weasel a job working for his organization; Changing up his tactics to throw off Taskmaster's powers, DP takes down the villain but not before having his middle finger cut off.
Release Date: 1997