Many thanks Amuk and Gavin, this is all great info. And yes that's the sword that Gavin posted above
.
To add more grist to the mill, this sword also bears a Latin motto - that of Sarawak as it happens - 'Dum Spiro Spero' (Whilst I breath, I hope).
This motto is carried around a stylised letter S. The S could stand for Sarawak, but if so, I have never found any other Sarawak emblem like that.
Perhaps the S stands for a region of Sarawak, or somewhere else entirely... such as Sumatra.
I initially assumed that this sword was that of a British officer serving under the White Rajahs (Charles Brooke to be precise), but I am now less sure.
The Java examples posted by Amuk above certainly seem to match very closely.
Thanks,
Matt