ERN C.Friedrich razor honing

Few hours ago I recived 6 ERN, C. Friedrich straight razors. They are more than 60 years old.
Razors are not shave ready and they need honing. Also there is some black rust pitting on the blades.
But main problem is when I try to strop razors the edge bends-"flexible" (they are very thin, thinner than any of my new singing blade) I do not use pressure when I stropping, not newbie to stropping.
So I need some help how to hone this razors, do I need some special technique or I can hone them as any other straight razor.

I would hone them like any other razor, but just be careful when you're stropping. I can't imagine that it flexes under it's own weight, so just be careful on your pressure and you'll turn up fine.

What about pitting?
There is pitting near the edge, is this razor usable or not?

If there is pitting in the edge, it'll have to be honed through. The only way to really know is to hone it till you do get a nice, clean bevel. Any pitting above the edge is only cosmetic... unless you wear the blade into it.

You just have to use light strokes. And yes some ERNs have very thin edges. If you read the history of the company they were the pioneers of the high tech at the time - hollow grinding.