I believe the key to designing a weapon that straddles two classes of existing items is to make it versatile in that it can be used two ways, but not as good as the originals. Make it a jack-of-all-trades & master-of-none, and when I say all trades i mean just swords and double-handed weapons!
It should be cheaper than both weapons separately, but not compete with either one on price or ability, quite a daunting task!
So with that said:
As a one-handed sword the unwieldy rule is appropriate, and makes it not quite as good as a sword.
A parry when used two-handed is very powerful. But if you take that away it would just be a halibard. -1 initiative as you suggested isn't that complex, ithilmar weapons add one so there is already precedent for that type of modifier.
I suggest keeping the one handed feature as is and changing the two handed to either -half initiative or -1 initiative and always strike last when tied for initiative.
Parry is a tough question, realistically it should allow you too, parry, but more drawbacks are required to make it work. Possibly, -half initiative is more of a negative than I think it is and a parry could be allowed with that.
The price you listed sounds good as a rare item, or 20 as a common.
And that's my two cents!