Hmm, really? Personally I've always considered the morning star hilariously overpriced, to the point I added a rule to the Globadiers in my Skryre warband(can only use a single one-handed weapon) specifically so it would have a reason to exist, as I've never once seen anybody actually take one even when I reduced it to 10gc in a campaign I ran - an Axe will do almost as well against most enemies for a third(or half, post reduction) of the price, and if someone's looking for a Strength boost everyone I've played against has taken the reliability and reduced cost of the Halberd over being able to carry a shield as well.
My rationale for the Khopesh was Sword + Axe = 15, but Difficult to use knocks it back down again. Otherwise why wouldn't you just buy a Sword and an Axe?
EDIT: To clarify the previous, I see it this way - 15gc gets you a Khopesh and a Shield, 20gc gets you a Sword, an Axe, and a Shield. You save 5gc on the Khopesh/Shield combo because you can only ever use one "mode" and the shield, whereas with the Sword, Axe, and Shield you can choose either "mode", or you can fight with both weapons at once for the extra attack. Since you get less with the Khopesh/Shield combo, it's only proper it costs less.