Today got an interesting issue.
For the same word or excel file, we can go to the list view, click the "Edit in Microsoft Excel" from the context menu, then open it through Microsoft Excel 2010 and edit it without any problem. However, on one computer, when trying to open it from search result, it is always opened in "Read-Only" mode, and no way to modify it!
Compare it to other computer, the light yellow warning message bar "Server Read-Only This workbook was opened from a server in read-only mode." and button "Edit Workbook" is missing from MS Excel program.
Since the problem only happens on one computer, there must be something wrong in that environment. After some struggling, the solution comes quite simple: just need to enable "Office Document Cache Handler" add-on in IE.