We have mentioned the free Forward Reply, and Edit app before which lets you edit the content of the forwarded message before replying. This fixes one of the complaints people have with BlackBerry email where it does not allow you to edit the history of a message when replying and forwarding. That original free version did not work well with OS 5.0 and slowly less and less people used it though it is still available.
Robert let us know that Bberryapp has revived the application and turned it into a premium application along with adding support for OS 5.0+ and the ability to edit a forwarded email AND still leave the attachment. The new Forward Reply, and Edit With Attachment app is up to version 2.2 and is available in App World for $2.99. I do not think you can upgrade the free version to this version but either way I recommend uninstalling and reinstalling it.
Let us know if you give it a spin!