Ancient writers made their point with it (8)
I believe the answer is:
penknife
'point with it' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe there's an association between them I don't understand?
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for penknife that I've seen before include "What may be used for carving" , "A Swiss army one has several blades and many tools" , "whittling tool" , "Small pocket cutting tool" , "Handy little gadget" .)