There's a keyboard shortcut to update all resources. So when I'm in the game and The diamond sword in the pack change it is not updated, but there's a key combination with which I can update the whole game. Does anyone know?
No, there's not, because the pack is not updated and should not update, this is more resource efficient.
How do you mean?
You can easily reload the resource pack data with the key combination "F3 + T".
There are also some other useful keyboard shortcuts that you can invoke with "F3 + Q".