You can use a grinder but a file is the best, just file the blades along the same angle as the factory has them filed.
How Do You Sharpen Scissors?
While I would recommend taking them to a professional (it's relatively inexpensive) I see that you are in the DIY section. I have cut sandpaper with my scissors before. I've also used a whetstone. ..kinda tricky regarding care instructions. You can purchase a whettstone at your local hardware store and they can guide you on how to use it.
There and jigs and shapening tools that include a stone and will hold the blade at precisely the correct angle. I haven't used a file on the blades of *any* of mine yet. I did use a file on the burr on a pivot once though, to un-sharpen it.
Compare sharpening cost to that of junk kitchen scissors at a Dollar Store or similar. Cheap scissors won't to really good, but you won't need to deal with super-cleaning them either. Kitchen shears get BAD fast, even with running them through the dishwasher unless the blades can be routinely separated for cleaning.
Added material:
Ace Hardware and other places have a nice tool for this:
www.accusharp.com
Compare sharpening cost to that of junk kitchen scissors at a Dollar Store or similar. Cheap scissors won't to really good, but you won't need to deal with super-cleaning them either. Kitchen shears get BAD fast, even with running them through the dishwasher unless the blades can be routinely separated for cleaning.
Added material:
Ace Hardware and other places have a nice tool for this:
www.accusharp.com