Boyd’s Bible Dictionary:

(waster). Primitively of stone or bone; later of metal. Little used at meals. For killing and cutting (Lev. 8:20); sharpening pens (Jer. 36:23); pruning (Isa. 18:5); lancing (1 Kings 18:28).

From Manners and Customs of the Bible:

Joshua 5:2. At that time the Lord said unto Joshua, Make thee sharp knives.
Knives were made of flint, bone, copper, iron, or steel. Specimens of ancient Egyptian and Assyrian knives are to be found in museums, and they probably have a general resemblance to those used by the Hebrews. They are of various shapes, according to the purpose for which they were made. Knives were not much used at meals. Even to this day the Orientals prefer dividing their meat with the fingers.