I've never been an archer myself, but as a crossbowman I can rack up a considerable amount of points by targeting horses and non-shield carrying personnel. Not always enough for valor though of course.
As a supporter of the idea of an extra reward for performing even after having achieved x5, I think only having the option of retaining a high multiplier after facing a loss (though is a great incentive to fight hard to retain in my opinion) may be lack luster to some. In light of the subject, ideas of options such as the availability of an extra "hard set" amount of gold or experience and perhaps even both makes for a delightful reason for all to achieve much higher than say "x5 and done".
My reward option would be perhaps, in the idea of role play, a message come across "[playername!] Thine repairs hath payed forth for your continuance of Glory upon the field of battle!". Maybe even introducing a game system for post x5 called Glory (name subject to change in accordance)