TibiaQA is like a wiki - that's why it should be possible to edit any questions and answers. Of course, reputation points are nice, but they shouldn't be the primary factor that drives the user to contribute to TibiaQA. Posting the exact same answer with small modifications is discouraged per TibiaQA guidelines (can result in downvotes, flags, or being completely removed).
Even that, I think if you leave a comment under a post that you edited, and state what was edited, users may up-vote you if they see that contribution valid. In the future, maybe it would be nice to add a small bonus for edits on other users posts, but this can lead to senseless edits.