score:19
Look at your same document , pg viii(pdf page 18), which defines the abbreviations used. Qua is listed as
Upvote:1
It is probably the abbreviation for a "caliver" - a type of arquebus
UPDATE:
I just found an online copy of the Subsidy of Armour, published by the Lincoln Record Society. In it, the items enumerated are listed in a footnote. A "Que". is indeed a caliver in this context.