The simplest would be to just retype the pass. if you don't know it, then you cannot access the password saved. Here is an explanation. And if you can, configure a certificate authority and a key (That would be shared between your iPhone and iPad) to access the Wi-Fi.
Unfortunately, on the iPhone it is not possible to access this information. The passwords are kept on your phone in a safe place that is not accessible through any regular means on the phone. This is done for your protection, if you were to lose your iPhone and someone picked it up, the passwords that are stored on it would be up for grabs. This would lead to a lot of security problems.
I would recommend apps like 1password or the many other pieces of software out there that do the same thing to keep your passwords safe and backed up. I have way to many passwords to remember and it has been a life saver. 1Password even has the ability to back up your passwords to dropbox just in case something happens to your phone and you need to access it from somewhere else.
There are a lot of different password managing apps out there, just find the right one for you.
As gtm above me stated, there is a way to access your passwords but it is through jailbreaking. I do not recommend jailbreaking, that is something that you have to make the decision on for yourself. Jailbreaking is not for everyone.
I know this may not have been the answer you were looking for, we have all been there when we forget a password and there isn't a way to retrieve it. The easier thing you can do is just reset the password on your router and make sure to keep that password safe.
I hope this answer helps somewhat.
quotation from answer by @de_an777
I just noticed you seeing this quotation because of the link to the thread. You unfortunately cannot bypass it. At least nobody found out (ostensibly). You could be the first one to discover ;)