Agree with everything said by Cattus. A few years ago I bought SigMaker from FontLab for 30 USD, but the current version on the FontLab website is still a PowerPC app which no longer runs on modern Macs. Apparently FontLab has decided to let it die, and my very occasional need for a font editor does not justify the price of a commercial font editor. For occasional use, FontForge is a good replacement for SigMaker, and I thank the developers.
I needed to tweak one glyph in one font. When you launch FontForge, Mac OS X will probably tell you that you need to install XQuartz or X11. Follow the link given by Apple and do it. Then, FontForge will run. It's weird. X11 apps are like Windows apps. They do not use the main menu bar, so you need to use the menus and buttons in the window. Remember it's free, so don't complain! Just roll with it.
I was able to figure out how to do what I wanted and get it done in about 30 minutes. The technology of fonts is deep and wide, and if I had any idea what the hell I was doing, it would have been much faster :)) FontForge does have a Help menu which can help you out.