I have always ruled that the Material Bonus of any item only applies to the item's Strength and Breakage Checks. I have NEVER allowed an item's Material Bonus to apply to OB/DB.
I may be assuming incorrectly that you do not possess it, but have you read the newer
Treasure Companion?
There are three different types of spells that impart a bonus to items: Weapon I-V, Armor I-V, and General I-V.
Weapon applies a bonus to items intended to be used as weapons: swords, staffs, arrows, maces, etc., etc.
Armor applies a bonus to items intended to be worn/used as protection: armor, clothing, shields, greaves, etc., etc.
General applies a bonus to all other item types: lock picks, rope, cooking pots
, belts, scabbards, etc., etc.
Then comes the question of bows and arrows. I have ruled that bow with a bonus is used for "hitting" the target. Arrows with a bonus actually applies the bonus ÷ 5 to the critical roll, not "to hit" the target.
For example, say a person has a +15 bow and +15 arrows. The +15 for the bow is applied to the OB. If the arrow hits AND achieves a critical, then the critical is modified by a +3.
I also have ruled that a +20 sword has a +20 "to hit", AND if a critical is achieved, the critical is modified by a +4. This is to show that a "magical" weapon is more deadly than a normal weapon.
The same is applied for armor/shields, except the bonus applies a negative modifier to the critical roll. Example, +15 armor would have a +15 to DB and a -3 modifier to any critical.
Of course, others will disagree with me... Some may even like my methodology for bonuses.
rmfr