How do I edit my saved words dictionary?

There is the slow way.

"To reject the suggested word, finish typing the word as you want it, then tap the “x” to dismiss the suggestion before typing anything else. Each time you reject a suggestion for the same word, iPhone becomes more likely to accept your word."

And the fast way.

Reset the keyboard dictionary: Choose Settings > General > Reset and tap Reset Keyboard Dictionary. Resetting the keyboard dictionary erases all words you’ve added, and you can start over with a clean slate.

BTW, the other instruction is: "To use the suggested word, type a space, punctuation mark, or return character."

There is no way to manually edit one word in the dictionary.

And here's another application: Dictionary Cleaner at http://www.twoamsoftware.com/?q=dc/about. It's old but appears to work.

I just stumbled across an application that appears to do the job: Dictionary Editor by Pariahware at http://pariahware.com/dictionaryeditor.php. It's freeware. It has no documentation as far as I can see, but then it probably doesn't need any.