But that scripts contains passwords which should be confidential and should not be viewed by the particular user, where he should have a execute permission alone for the two files.
Then also the specified user can use the default editors and viewers.
Uh.. no. The user will NOT be able to view the file contents, as he won't have permission to use any of the text editors. He wouldn't be able to cat, grep, vim, nano, emacs, more, less, or anything else. He will be able to execute the files, nothing else.
That's the whole point of only giving him access to the "secure" group's files. Unless your permissions for your executables are screwy (i.e. world-executable), he should be unable to use them.
You could also set the script permissions to --x, which would prevent him from reading the files even if he DID manage to find a way to use a text editor.