just so you know . . . Shakespeare is not always easy to understand even for modern native speakers. The meaning here is pretty literal; he's just saying it in a complicated way. TAKE ARMS AGAINST means fight against, using weapons. BY OPPOSING END, means that by fighting against (the slings and arrows of outrageous fortune, sea of troubles, etc.) he will end them. You probably know this already, but this speech is a person considering whether to kill himself .