I use mine all the time, have a variety of belts for it from 40-grit all the way to 15um polishing belts. The first thing I did was remove the table and the side-cover, push out the platen and curve the top of it allow a smoother transition, then i flipped the thing on it's back so i can actually use it, and now it is good-to-go
I can sharpen everything from lawn-mower blades to little stockman speys on that thing, and a reprofile takes very little time. As mentioned above, all you need is sharp belts and a careful hand.
I have to admit that I never really looked at it that closely. Over the years of having my woodworking company I have acquired 3 different stationary sanders, one being a 1" Delta many years ago. When the HF didn't work out right away, I dismissed it as "it is the wife's, not mine" and "that's how HF is, hit or miss". Never gave it a second look or second thought. But thinking about what you with it, I will probably take it out (still in the original box!) and try it out with your modifications.
I have not tried it with broken glass, that sounds more like a problem of choosing the right belts for the job...
That was pretty popular with her and her girlfriends for a while. That, and drinking a lot of white wine while designing, grinding and gluing. The little machine worked great for them with the stock belt. Turned out to be a passing fancy, making me thankful I didn't spend a lot on a sander that I would by for the wood shop.
Regarding light-weight, you can secure it in place, don't get why that would be a problem. Regarding no "good place to put the knife",
you hold it in your hand and place it against the belt... 
Do you mean you want an angle-guide of some kind?
LOL!!! So that's what I have been doing wrong all these years! I was holding the knife between my toes!
Seriously, I have been sharpening on my Delta 1x30 for about 20+ years. I always hand finish. And for me, I never use it on my knives. But I have a little side business sharpening for my friends and for a medium size business. They don't take care of their knives and I found that after I committed to sharpening they cleaned out their drawers and I got knives that were chipped, bent, edges bent in different directions, etc., and I couldn't charge enough to work those out by hand. About 30 years ago I had a friend that was an older fellow that used sharpen my circular saw blades. When things started to change over to carbide which the old C2 stuff we used until it was dull then threw away, he was out of business. (C3 and C4 you can sharpen.)
He needed the income, so he took his saw blade setup out of his little mail truck, and put a homemade belt sharpener in the truck. The sharpener was easy to use (just a slack belt setup) and it was easy for him to make. He couldn't find any belts locally, so he bought them at Grainger supply. He could grind out chips, straighten edges, sharpen, then hone a damaged knife in minutes. That always impressed me. He didn't get a lot for sharpening (I don't either...) but he was really fast and could tear through a restaurant's kitchen knives at warp speed.
He was the one that showed me how to sharpen on a "slack belt", grind out chips on a platen, and polish the edges holding just off the guide wheels. I was too lazy to build one like his 30 years ago, and only tried the Delta on a lark after watching a friend of mine edge his damaged hatchet on a 6X48 belt sander.
May give the old HF another look. If I take enough pieces off and lay it over like you are describing it might turn out to be a good tool for me. I'll keep your tip in mind and make sure I am wearing my shoes (so I remember to use my hands!) when sharpening/grinding.
Robert
Felt the same exact way when I unboxed mine!
