With all due respect to your expertise, PF is a terrible simulator (e.g. blades too heavy, loading too fast), and we should be figuring out how it works on PF terms, rather than dismissing it because of poor IRL stats.
I personally go with reach XOR twf with either end, finessable in either form, trip on sickle, disarm on ball.
Amusing. Go look at the dreaded Katana threads. And do not cite me having 'expertise'. I noted that I was the worst student in the class. And D&D has always been abstract at best, so I agree with you there. The reason to have a K is in the coolness factor and to replicate some of the myth. If you're just creating a purely fantasy weapon, have at it. The posts I was trying to add facts to were all about how the real weapon is used.
In my game and several I play in, EWP grants you 'tricks' valid for that weapon, many of which are otherwise sub-par in some way. A sword our Fighter picked up has no guard of any type, no 'fighting defensively'. A piece of *, but it is enchanted and has an EWP bonus I do not know.