Dan, you failed to cite any specific examples, but your question made me really curious as I have examined a lot of personnel records (but only post FWW) and not come across the VB designation. Your comment about a "Victorian" decoration, made me think it might likely only be a "Victorian" term (or pre CEF anyway). Hopefully my own search in 19th Century Gazettes have turned up similar references to what you have searched??
I think VB is not an award/decoration but indicates a certified qualification.
In the couple of Gazettes I looked at from the 1870's and 1880's I saw the post nominal, "v b" and "V.B." many times. But seemingly only in conjunction with citations of promotions & qualification.
From "Sessional Papers of the Dominion of Canada, Volume 21, Issue 11", 1888
i.e.: "Jones, Thomas Henry (v b 2nd) 3 Apr 84"
From Canada Gazette, No,19 Vol.V, November 4, 1871:
"Confirmation of Rank. The following Officers holding certificates of qualification are hereby... Major John Murray, V.B., 1st Class, 20th Battalion, from 30th September, 1871."
Some citations list a "vice" after the name. I'm not exactly sure what this refers to, but it seems likely to be the person they are replacing?
"To be 2nd Lieutenant, provisionally: Private George Henry Williams, vice E. Horton, deceased."
"71st York Battalion of Infantry, N.B.. To be Lieutenant Colonel: Major John Lothrop Marsh, V.B., vice Hewitson, resigned."
The abbreviations listed on page 249 (of the PDF) from "Sessional Papers, 1888." (Appendix No. 15, The Militia List of the Dominion of Canada) list numerous "certificates" of qualification, among them are:
r m c ...Royal Military College Certificate
r s a ...Royal School of Artillery Certificate
s c ...School of Cavalry Certificate
s m i ...School of Mounted Infantry Certificate
s i ...School of Infantry Certificate
m q ...Military Qualification Certificate
v b ... Board of Examiners Certificate
All the other abbreviations make sense. How or why "VB" stands for Board of Examiners Certification??? I don't profess to truly understand this material, but I think this is the likely explanation of what you have been seeing.
BTW I only skimmed "Sessional Papers" but saw a lot of interesting data on the state of the militia at that time, interesting reading.