There are a few interesting points here.
From a photo, bog oak and ebony would be almost impossible to distinguish. Bog oak is lighter and quite soft to carve, while ebony is very heavy and hard.
I believe the hilt of this knife is a variety of ebony.
The blade looks very similar to some Philippino daggers I have seen.
So my guess would be a Philippino dagger, with a replacement hilt and front bolster.
