Finally made enough attacks with my enchanted cryptchill carbine to have statistical evidence rather than just a vague sensation that it decays a lot.
The wiki says weapon attacks are a 2% decay rate, over the last 496 attacks my carbine has decayed 19 times a rate of 3.8%. Over that data set it my bad stat analysis gives an over 95% chance that I haven't just got unlucky.
My best theories are:
The event weapons have a higher decay rate for some reason. I don't have any data to disprove this one.
The wiki is wrong about weapon decay rates, though that one actively made its way into patch notes at some point so seems unlikely. Might be the case that it's a value stored in lots of places and the ones that were changed weren't the ones the rng actually calls.
Enchanted weapons call decay twice, once for the main hit, once for the supplemental damage. Was my favourite default theory. When I get the last few cold enchants off the carbine and swap it to accuracy I'll start collecting data to see if it's different.
Feels worth having a bit of a look at the decay code to see why the rate is near double, even if largely only fallen actually care about non-innates at T3.
The code on this is pretty concise and says it works like this:
The base weapon decay rate is a game-wide setting defined by dev tools. Currently this is 2%. Prior to April 19, 2025 it was 3%. The code handles this in only one place.
The code and database does not store separate decay rates for different weapons.
If the weapon is melee, hand-to-hand, or a throwing weapon that isn't a Sling and the target has the Parry skill, the chance is increased by 6%.
The chance is reduced by a percentage equal to the number of Durability enchants on the weapon, potentially down to zero.
The Prayer result Weapon Turning and the Elementalist's Wind Wall each increase the chance of an attacking weapon degrading by 5% if the target has it active.
The Prayer result Unbroken Bond negates all chance of weapon decay if the attacker has it active.
However, there's a pretty significant bug that came up here - the linking of decay chance to a game setting (currently 2%) in 2025 was done only for attack code vs players and pets. It wasn't properly incorporated into attack code vs structures or target shooting - those were still hardcoded to the old 3% number. So that'll be resolved in the next patch. If your attacks included bashing and target shooting, I think it's safe to assume that this is the cause of your observed anomalies.
