Historical information
The origins of the pen rack probably began when quill pens were being replaced by steel nib pens that were held at oblique angles for writing this method of writing started to gain popularity around 1820-1860. To understand the development of display racks to hold pens on a desk we need to understand the development of the pen itself.
Before the early 19th-century steel pens were almost universally all barrel pens affixed to a holder pretty permanently. Pens were also not disposable. There were even steel pen repair services, just like the same services around at the time to repair you're fine quills.
Individual slip nib pens which fit into a holder were originally pieces of a quill which came in a box of nibs and fit into a holder. These were disposable and meant to obviate the need to mend your quills. By 1831 you start to see more what they called “slip nib pens” or “portable pens” (easier to carry than a long barrel pen), but the idea of holding the nib at an oblique angle in the holder was an idea new enough that it warranted a patent.
In 1831, an enterprising and very successful stationer and inventor, Sampson Mordan (inventor of the silver mechanical pencil) combined with one William Brockedon to patent the first oblique pen and oblique holder. In the patent application, they mention as the benefits that this would allow the writer to hold the pen more comfortably as well as it should allow the pen to last longer since both tines will be moving across the paper evenly. It appears at the time the idea of holding a pen obliquely was new. As a result of the popularity of the oblique pen many different designs of pen desk holders were being made, to keep pens suspended on a rack alleviated the possibility that the expensive new steel nibs with their holder could be damaged if left in a desk draw with other items.
Physical description
Double sided Pen Rack, decorative metal with four metal legs