Imo buffing polearm speed doesn't make much sense, except if you compare it to 2h speed and the way polearms are handled.
Other than that, polearms are probably the most clumsy (and not in absolute terms, as military stuff it has to be usable) weapons we have, or at least they should. Giving them more speed is not a good idea, especially given how pole animation sweetspots make both castor swings and turning into your swings to accelerate them very easy. More damage would make a lot of sense though.