Microsoft's Outlook email app for iOS now offers better integration with the Microsoft Office productivity suite. Of course, you need to make sure you have the Office apps installed on your phone. And if you do, you'll be able to open and edit attachments easily and send them back with ease. You just need tap on the "Open in [Office app]" button make your edits, and then tap on the back button to head back to the Outlook app. It'll attach the edited document for you. 

Source: Lifehacker | Download: iTunes App Store (Free)