qpdf is good for e.g. removing any password protection - given you know the password. But I kinda doubt that's what's meant with editor. And quite frankly, you can do most of what qpdf does more comfortably with tools like PDFSam or PDF Arranger. The latter even lets you crop pages or rename the document name (saved inside the pdf). If you want a reason to go CLI, that's definitely ghostscript. It can compress (losslessly), decompress, resize images and pages, have it conform to various PDF standards - to my knowledge pretty much the only free piece of software that will write PDF 2.0 compatible files - merge files, embed fonts/font subsets or convert them to outlines, convert to images...and that's far from a complete list. Of course it's quite complex but there are many pages out there that will tell you how to achieve what. I doubt there's a single program as capable as ghostscript - maybe with the exception of Acrobat Pro.
Richard