What age or era can this bayonet be estimated to be from? The grip was likely originally made of wood, but has worn away over time. The weight of 240 g refers to its current condition without the wooden grip.
Yes, it's a bayonet. It looks like it was also used as a civilian knife. The blade has been shortened and has seen a lot of use, as the edge looks very worn.
I've uploaded more photos showing it cleaned, along with additional information. Based on my research, I'd guess it's from World War I, but I could be wrong.