As long as you are doing usual processing, hardener is unnecessary and undesirable. Hardening fixer takes longer to wash out. That powder in yellow bag works slower and washes slightly slower (because it's not that strongly hardening) but otherwise the same.(posted 8185 days ago)If you are looking for a non-hardening rapid fixer, I recommend Ilford Multigrade fixer.
If you like to know a lot more about the choice of fixer, there was a lengthy discussion on the topic before so I suggest you search for it.