What skills make for an excellent Goalkeeper?

[Celtic]

I have been assuming that Handling is the most important and that offensive skills are not at all important. Am I correct? What are your thoughts?

Being a GK he already has exceptional defensive skills.

If you think that channeling all training to Defence will make him better, you may start building a slow GK with terrible foot work who makes dreadful passes and takes terrible decisions and goal kicks like Pinto or Artur, instead of a completely fit keeper like Neuer or Navas.

Then again we don't know how performance is calculated, so this is all academic moon talk from the realm of monetizing fantasy.