The knife has two effects: it gives a 5% chance of getting double arrow shafts from fletching Logs, and it gives a 5% chance of giving a strung bow instead of an unstrung bow when Fletching unstrung bows. Experience for stringing the bow is given as normal and it will still count towards any daily challenges. The knife will consume 3.57% charge per activation, or 1.78% in Prifddinas, thus lasting 28 or 56 times before degrading back to a crystal tool seed. The tool seed can be recharged by Ilfeen, Eluned, Islwyn or Rhodri Dail for a cost that starts at 7,500 coins but decreases by 1,500 every enchant, to a minimum of 1,500 coins.
Cost for re-enchantment
Fifth and thereafter
You can also talk to Ilfeen, Eluned, Islwyn or Rhodri Dail if you want to turn your knife back into a seed.