This is in the general style of Mahdist display/ceremonial weapons from Sudan, which are often densely-covered by inscriptions. This one has inscriptions in the main cartouches, and the rest of the surface is covered with what might be inscriptions, but might also be random scribbles intended to look like inscriptions. These inscribed weapons were intended as badges of rank or rewards for meritorious service, which doesn't require them to be usable for fighting. However, some were essentially functional weapons, and might have been equally intended for fighting, like this kaskara:

• https://historical.ha.com/itm/military-and-patriotic/19th-century-sudanese-kaskara-mahdist-islamic-prayer-inscribed-broadsword/a/6070-3.s

These weapons were made in both Persian/Arab styles, such as this haladie (a double-edged knife from India and Syria, of which there are many Sudanese examples):

• http://www.swordsantiqueweapons.com/s999_full.html

and these Persian Dervish-style axes:

• https://www.ashokaarts.com/shop/fascinating-group-of-mahdist-sufi-moslem-weapons-from-the-sudan

Others are based on African weapons (such as the kaskara sword above), such as these throwing knives:

• http://www.karlssonandwickman.com/tribal-weapons/sudanese-throwing-knife

• http://www.sothebys.com/en/auctions/ecatalogue/2012/africanoceanic-n08858/lot.79.html

This unusual weapons combines both Persian and African elements:

• https://www.britishmuseum.org/collection/object/E_Af1936-0508-8

The time between the end of Mahdist rule in Sudan and WW2 would have given this plenty of time to make its way to Indonesia. There are, of course, modern fake antiques of this style, but if it was acquired during or just after WW2, it is likely to be a genuine Mahdist item.