There's plenty of ways that this can be done, including fiddling around with sword skills, damage, adren costs, etc.
But I think my personal preference would be to give swords a faster attack speed, rather than equal attack speeds between swords and axes. This might be my personal bias showing - I like looking at fast attacks

Another option I favour is to make the sword-related tactics skills less trash-like. (riposte, etc.)
We can also make Hundred Blades useful enough to justify its elite status. Or make it less useful, and make it non elite. I'd like to see it have a lower recharge time (say, 5 secs), and retain its elite.