The thinner end does look like it was a tang and was in something like a
handle. However, if the entire item is 22.5 cm long, the thinner end is too short to be a
handle on its own.
Maybe it was only inserted partway into a longer
handle - but this makes for weak construction. This is why the tangs on genuine knives, daggers and swords go through the entire length of the
handle and usually out the other end to a pommel.
The other option is that the thinner end was inserted into the
wood of a cart, boat, door, chest, wall, etc.
Likely impossible to discover the exact purpose.....
SC