Good idea. A lot of people would use a pick, but don't want to look like a coal miner. A Spathovaklion with no knockdown but pick-like stats would be an interesting niche. With the current stats, it's a spammable knockdown machine with good reach, so pretty OP.
Knockdown is kind of lame to be honest and I say this as someone who is a big fan of abusing it in strategus. Not very thrilled with random "stuns" like that in game. It should really be limited to big, slow and heavy weapons like the m.hammer, iron mace, and w.hammer. The 98 speed maces are borderline but the the flanged mace and spatho are definitely on the wrong side of the acceptability line for knockdown spam, they are light, fast 2.0 lightweights.
As you said I think it would be more interesting if they occupied a niche of non-knockdown blunt, up the damage a bit so they don't crutch knockdown spam, and they compete with pierce picks as can-openers.