What type of saw to use on a wall of windows, removing glass but keeping wood framing
That looks like regular dried-up old glazing putty. If it was me I would soften it using a heat gun while scraping it with a putty knife or similar tool.
Then I would rig a guide on my router and remove all remaining putty (and maybe a thin bit of the wood) with the router. I might use a paintbrush to soak it with mineral spirits prior to routing, to reduce dust.
If I were worried about asbestos exposure from this job (I wouldn't be...) I would wear a P100 respirator and tent the area with plastic to contain dust. Risk would be low with this short-duration job, especially considering that the bulk of the suspect material will have been removed manually prior to using the power tool / dust machine.