If you don’t mind converting the Excel file to CSV, csvkit[0], which is mentioned in the list, has a tool to pipe Excel into CSV for further processing by its sibling tools.
It won’t help if you need to retain anything Excel specific, but I find it very useful to deal with any Excel files that come my way.
Yes, there are multiple Python libraries for wrangling Excel files as well as good built-in CSV support via the stdlib's csv module - which, despite its name, can actually support DSV (Delimited Separated Values), which is a generalization of CSV. The csv module also has a dialects feature with attributes like settable delimiters (which is how you get the DSV support) and quoting. And since Python's built-in data structures like lists, dicts, tuples and sets are great for munging data, you can get a lot done with just that, plus the benefit of Python's readability and productivity.
Edit: I’m looking for a command line tool that allows me to open an Excel file, make a few simple changes, and then save again as an Excel file.