...I rarely see publicity items in glass, for glass companies, and know of very few examples....
They appear regularly and are obviously often made by other companies.
Owens Illinois: glass figure (Venus), Bust of Owens, promotional printed tumblers.
Hoskins Rose, Paperweight in the form of a mirror.
Moncrieff: Paperweight, and one they made themselves

Glass tubing acid etched Use Moncrieff Inks, a nice tie between two parts of one company.
Regularly see other items on eBay and always hotly contested, particularly American glass companies.
Paperweights are probably the most numerous type of promotional item but they are also commonly non-glass... see cut throat razor here
http://www.ysartglass.com/Moncrieff/Moncrieffgauge1.htm (and paperweight). Moncrieff also provided steel tube cutters embossed with their advert - an essential tool for any of their Gauge Glass customers and thus a most appropriate form of advertising. They also marked every bit of tubing sold.
The point being that not only are these items relatively common, they are clearly out-sourced and not necessarily related to the companies products. The target being something that the recipient will want to keep and probably on display. No doubt there were companies specialising in such products and it is possible that the glassworks are even unaware who made the actual item.