I've recently visited one Polish museum with the medieval weapons and what struck me was that the "militia" spearmen were usually equipped with the axes as well. This reminds me the SSHIP system where you can have a militia unit with axes (it happens to be better in attack but worse in defense, iirc) and another with the spears (better on defense, but killing slowly). I think it should be done in a different way: one unit but with spears as a primary weapon and axes as the secondary.
What are your, PB, thoughts about it? (well, I don't know, fe, the mechanics of switching from primary to secondary weapons - what's the delay, when the units do it with player pressing Alt etc.).