This is four dumbell shaped American Brilliant Period Cut Glass Knife Rests.  The balls are multifaceted and the bars are six sided.  They are 4 1/2" long and the ball is approximately 1 1/4" in diameter.  Two of the bars have slight roughness that is not unusual.

The height of use of knife rests was during the Victorian era where they were placed on the table with a matching salt dip and spoon.  The knife was only placed on the rest during changes of courses at dinner.  At other times it rested on the edge of the plate as it does today.  They continued to be used at formal dinners until the  1930s.  Now they are used for decorative purposes and for paperweights.