I dont see why one weapon would perform worse - in this case.
Just because it has been done like that in some other games, in some other systems. i dont see any need for that here.
In OS daggers deal relatively low damage, and i havent found any especially powerful. the most was one with 50 max damage.
That is balanced by the fact that you perform more attacks in your Turn.
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I also dont see what would be the point of using one dagger but splitting that into two... animations?
It would be much better if we could use two daggers, a punch dagger or Rondel-dagger combinations - as i suggest. That way we can combine two weapons with two different kinds of stats as we please.
But - for double the AP cost. Or Sum of the two AP costs.
Damage can be further reduced for specific weapons if that would be necessary.