I recently acquired these two Batak knives which I don't know either the name or the function.
The first has a handle similar to some Lopah Petawaran seen on the internet but the blade is much simpler.
Blade length : 16cm
Handle in Saro (Capricornis sumatraensis) horn with silver
This one (with the silver bands at the hilt) indeed resembles typical LPs: It is a known type that usually comes with a simple blade (without an integral bolster) and a only slightly curved hilt that usually shows an exposed tang. On average these seem to be a kind of poor cousin of the typical LP; however, there are a few examples with fittings that suggest higher status wear (as well as pretty basic typical LP). Whether this is a LP variant or a related but distinct type is probably a moot point - I don't know of any primary sources which discuss these blades. Thus, no info on historic names, too.
OTOH, it seems very likely that these had the same ceremonial use as the typical lopah petawaran.
The second one has a blade very close to the Lopah Petawaran but the handle and the sheath don't look like what I saw elsewhere.
Blade length : 23,6cm
Handle in buffalo horn and brass.
Scabbard in wood, deer horn, bone and silver.
This blade might be of the typical LP type - could you please post close-ups of all 4 sides (of the base & bolster), please?
The hilt and scabbard are not traditional and obviously later replacements. These look like 20th century work while the blade looks much older...