Current Bane can allow humans to make an extra unit type. The thane (Viking tree).
These units are super cool but suck due to not having academy upgrades. I suggest removing this skill as it is useless.
Or better yet have the Thames gain upgrades based off your swordsmen upgrades since they are built from the same building.
If this is not possible due to coding. Then how about adding a new branch to the academy for Thames once you have the skill at level 4 or something I dunno.