In addition to using Open from Aras to open a document, you can also open directly from the Aras web client.
Note: This feature works only when running Aras Innovator in Internet Explorer.
Open the form of the desired document, and click on the hyperlink of the Office file:
You will then get a dialog similar to this:
Clicking on Open will open the file in the MS Office application. If you then click the Refresh button in the Aras ribbon, the file will be connected to Aras.