One of the changes in WordPress 3.9 is the removal of the 'Paste from Word' button and the accompanying improvement in the functionality of the 'Paste as Text' button.
There was a 'Paste From Word' button?
Yes, and it worked so poorly that I advised people not to use it. It would will your post with dozens of lines of in-line CSS styling that did nothing. I can't tell you how many times I've answered calls from clients asking me to fix 'something wierd' on a page or post they have written. Invariably they's composed the text in MS-Word and then done a copy-and-past into WordPress.
I understand the attraction of 'Paste from Word'. People are comfortable composing, editing, and formatting in Word. It seems very natural to be able to do that, getting the text, fonts, colors, sizes, etc just the way you want them and then just copy-and-paste into WordPress. O the siren call of that 'Paste from Word' button. And usually - just like the sirens in Greek mythology - it would end badly. The page that had ben beautifully formatted in Word would invariably look almost right in WordPress. Each attempt to 'fix' the formatting made it a little worse until the page looked hopes and they gave up and called me.
My advice has always been to compose in MS-Word but format in WordPress. By this I mean get the right in word, paste them into WordPress, then add the font sizing, color, etc in WordPress.
WordPress 3.9's improved pasting functionality makes this approach easier. Turn OFF 'Paste as Text' and feel free to copy text from your MS-Word document and paste it into WordPress now. Bold and italic formatting will be retained but all the other formatting codes will be cleanly stripped out - at least according to my testing.