I just noticed that the one that slipped by us last night has a brass hilt of similar form dto the bone one on my example in post #21 of this thread. Maybe this is a common Nias style. I am not sufficiently familiar with Nias hilts to know whether it is common.
I don't recognize this as one of the well established hilt types. Having said that I have to stipulate that there are not that many really old piso Nias around.
Your bone-hilted example seems to be the youngest; I'd guess it's post-WW2 (and probably not early in that period).
The second brass-hilted example that you got might be earlier but I'm not going to hold my breath... (niodanga wana)
The first brass-hilted piece has an interesting pommel (possibly alluding to the stylized southern Sumatran keris hilt?) and I'd like to see more pics after you receive it (and maybe some gentle cleaning)!
Detlef's wooden hilt might be the oldest among those shown here. Still, it's most probably from the first half of the 20th century; the hilt type (based on the Sumatran/Aceh hulu bawar - itself an extant survivor of early hilts from Java) is a well-established type also known from Si Euli.