Hi Jim, thank you for the information! I did not know of the designations for differentiating blade lengths and the possible associated with the Bengal forces with the 33” size. Your example is very similar and you’re lucky to have stampings attributed to the 21st calvary, a nice slice of history provenance. I will provide a few links that I have found if anybody is interested in some more information. The first: the Imperial War Museum, second: Australian War Memorial, and third: a brief Youtube video of the history and description of the type.
https://www.iwm.org.uk/collections/item/object/30001638
https://www.awm.gov.au/collection/C226996
https://www.youtube.com/watch?app=desktop&v=k92PstHFQRM
-Geoffrey