I think this is called a "roughener". It's used to prepare surfaces, for example before applying a layer or glue.

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Note added at 2 hrs (2015-11-02 09:22:01 GMT)
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There is a picture of one (or something similar) in this (German) document: http://www.goetz-service.com/web/pdf/goetzkatalog.pdf

"Patentaufrauhburste
kompl. mit Rauher, 20 cm
Hard roughener brush compl. with roughener,
8 inches Ersatz-Rauher
Replacement roughener"

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Note added at 2 hrs (2015-11-02 09:26:18 GMT)
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another German ref (with pictures):

http://www.hardo.eu/en/Products/Orthopedic-shoe-technology.h... -> http://www.hardo.eu/en/Products/Orthopedic-shoe-technology/A...

"Orthopedic shoe technology

Accessories

Trimmers
Trimmer guide discs
Trimmer heads
Drilling chuck
Rougheners
Polishing wheels
Grinding and sanding wheels
Rasp heads

[…]

Rasps and roughening tools
Egg-shaped rasps
Finger-shaped rasps
Special rasps
Orthopedic rasp tools
Drilling chucks
Rougheners"

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Note added at 2 hrs (2015-11-02 09:30:30 GMT)
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"Roughen surface before applying Shoe GOO."
"Before you start gluing your broken shoes, make sure that they are dirt-free, clean, and dry. Try to roughen the surface and keep the glue between 70 and 80 degrees ..."
".. Roughen the bonding surfaces of the sole and the half sole. […] How to Glue a Half Sole - HalfSoles.com"
... This creates rough surfaces that will help the new sole adhere to the shoe.

https://www.google.co.uk/search?es_sm=93&q=roughen surface l... (Google search for: roughen surface leather shoe before glue)

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Note added at 2 hrs (2015-11-02 09:32:40 GMT)
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"For supplies and tools, you need some of the following depending on what kind of shoes you will make: a form (pair of lasts, shoe molds) soling leather (veg tan, tooling leather), shanks or prefabricated footboards (which have the shank built in), heels (sometimes called heel blocks), heel tips (also called heel replacement tips, and sometimes called heels!), lining leather (which is very thin), toe box stuff. Barge cement (or some other really really good, but extremely toxic glue. A hammer and an awl should come in use. You might also need cobblers thread, shoe buckles, polish, dye, leather hole punch, rough grit sandpaper, fine grit sandpaper, a roughener (which helps the glue hold leather together)."

http://www.ebay.co.uk/gds/Shoemaking-supplies-cobbler-shoe-m...