Since 1.8 a sacrifice repair always costs 2 levels (plus any prior work penalties on either item), and likewise a unit repair (not possible with a bow) always costs 1 level per unit regardless of durability or enchantments:
Prior to 1.8 this was a very different story as repair costs were based on how much durability the sacrifice (but not target) had, ranging from 1-17 levels for diamond tools, less for other items (1-4 for a bow):
This made it particularly advantageous to repair items with slightly damaged sacrifices; for example, I use a diamond sword with Sharpness V, Knockback II, Unbreaking III, which would cost 40 levels, one above the limit, if you tried repairing it with a brand-new sword (otherwise, you can repair it with 2 diamonds but this doubles the resource and nearly doubles the XP cost per durability point restored, not that it matters for my playstyle and I repaired it this way for a long time), but by slightly damaging it the cost can be lowered to as low as 38 levels and you still get a full repair because the anvil gives you up to a 12% bonus based on the maximum durability, even if the sacrifice has 0 durability left (this is also the case in 1.8+ but less advantageous; in any case if you are in 1.9+ I'd get Mending on every piece of gear that you use at least regularly).
Simple question:
Repairing an Infinity bow on the anvil using a new unenchanted bow, does the XP cost vary with the current wear state of the bow?
TIA
Learn something new each day
Since 1.8 a sacrifice repair always costs 2 levels (plus any prior work penalties on either item), and likewise a unit repair (not possible with a bow) always costs 1 level per unit regardless of durability or enchantments:
https://minecraft.gamepedia.com/Anvil_mechanics#Unit_repair (sacrifice repair mentioned below)
Prior to 1.8 this was a very different story as repair costs were based on how much durability the sacrifice (but not target) had, ranging from 1-17 levels for diamond tools, less for other items (1-4 for a bow):
https://minecraft.gamepedia.com/Anvil_mechanics/Before_1.8#Costs_For_Sacrifice_Repair
This made it particularly advantageous to repair items with slightly damaged sacrifices; for example, I use a diamond sword with Sharpness V, Knockback II, Unbreaking III, which would cost 40 levels, one above the limit, if you tried repairing it with a brand-new sword (otherwise, you can repair it with 2 diamonds but this doubles the resource and nearly doubles the XP cost per durability point restored, not that it matters for my playstyle and I repaired it this way for a long time), but by slightly damaging it the cost can be lowered to as low as 38 levels and you still get a full repair because the anvil gives you up to a 12% bonus based on the maximum durability, even if the sacrifice has 0 durability left (this is also the case in 1.8+ but less advantageous; in any case if you are in 1.9+ I'd get Mending on every piece of gear that you use at least regularly).
TheMasterCaver's First World - possibly the most caved-out world in Minecraft history - includes world download.
TheMasterCaver's World - my own version of Minecraft largely based on my views of how the game should have evolved since 1.6.4.
Why do I still play in 1.6.4?
Thanks a lot. I put that link in my Minecraft folder to keep handy. Lots of info there.
Learn something new each day