I am not sure why it does pierce damage on overheads - it has a curved blade, but it is still a blade, not a beak. If it could have knockdown that would be more appropriate, but I think KD only works on blunt damage even if it has the KD flag.
Anyway, old Bill it perhaps the best 2-way polearm. It is not less useful than the Swiss, quite the opposite, except that the swiss is a bit easier to use in close quarters (which neither is very suited to). I don't consider "bonus vs. shields" a big thing unless you have a very high damage (40++) weapon that can repeatedly hack on the shield. The Swiss looks so cool and I suck so bad anyway that I used it even though I had 1 wpf in poles.