default weapons appear to NOT matter at all.
just checked the difference between dalinsa snow hunter (default weapon 1 h sword) and a berserker ( default weapon 2 h sword)
Both did the exact same amount of damage with either a 2h sword or a 1H sword.
i can always give the numbers if needed, but i guess you only care about the result.
And about their “special moves” i would say they do quite the same. Normally they try to alternate from 1 quick attack combo to a heavy attack combo. Once they consider their ennemy comes out of range they can break their combo chain to land 1 or 2 single hits but it’s not 100% consistent. Sometimes they will still try to finish their combo even if they are swinging the air.
hope that answers your question.