Is It a Perfective or an Imperative?

Different languages make different choices about what aspect to use with it. In classical Greek, the past imperfect with tealic verbs can have a commative interpretation - I tried to persuade or I was persuading. With atelic verbs you absolutely cannot have that interpretation. So that's a really subtle thing and a good way for your Greek instructor to torture you when you first read any big texts is to try to fish a try to reading out of you.