question about DI on crafted weapons

[BigL]

I have used a couple Heartwood Fletcher kits and I rarely get 40 DI weapons using ash. There is a few bows I got off a vendor that all have 40 DI on them and they are all ash. I know yew adds DI but is there anything else I am missing? What DI increase should I expect off an exceptional item? I am using a 26/30 fletching totem.

[Skrillex]

Di on ash bows are caused by: bowcrafting lvl skill
Arms lore lvl skill
Talizman excepcional

If weapon get the prop exceptional , it will be with 40DI

[Exillion]

the bow being exceptionally crafted adds 35 di
100 arms lore skill adds 5 di

[BigL]

ty all I didnt have lore

[Calvin]

arms lore also adds i think 5 random resist points to armour crafts