In password/security dialog there is only one field where password can be entered. I think there should be another field to confirm password, so that these two fields can be compared and if there is a mistake it should be shown, I mean user should be notified that they don't match. User can type in password in a wrong way and don't realize that, which can cause a lot of trouble.

I have just checked it. I changed admin password and when logged in I wasn't ask to set/retype password. And for changing password in Konsole an old password is required. When I make a mistake and don't have a note with correctly written password or I just first write type password on paper but then mistype one keyboard sign this would mean that I can't act as an administrator anymore (unless other tricks are done to change password from root account). 

Discussion and brainstorm idea:
http://forum.kde.org/viewtopic.php?f=113&t=102257

Reproducible: Always