Power tool for scraping paint off windows
No no no, you really don't want to do that

As Alaska Man says... "power tools near glass, what could go wrong?"

I strip a lot of paint off a lot of windows because I hate masking.  And it's not super-easy latex paint either - it's alkyds or LPUs (which are a fight) or worse, 2-pack epoxy primer, which has an uncanny bite on glass (how??)    Or silicone sealants.  

Just go to town with a bottle of Windex and a stack of sharp razor blades.  It's really fast work, and I don't see how a power tool could help. Keep the area wet with Windex.  If you don't want to waste Windex that way, dilute any lliquid soap; the purpose is to lubricate the razor blade to keep it from scratching and extend its life.  Let a good rain take the soap away and windex it at the end.  Do Not Do This Dry. 

If it's slow going, you're doing it dry, or using dull razor blades (change those lickity split, they are your enemy as they will scratch the glass!  Also, there are no medals/awards for conserving razor blades, and they recycle 100% because the landfill shreds your trash and runs a magnet over it to pick up ferrous waste).