Rather than cannibalizing magic items, why not have it be part of the Dragon's Hoard?

Silver Dragon's Hoard: The Silver Dragon maintains a collection of material wealth and magic items, a sprawl of coin and trinkets that fills a cave or room. Wealth is power, and the Silver Dragon can turn this wealth into personal power. The Silver Dragon can act as though it were wearing a number of magic items with a value up to half of the amount in its hoard. Further, the Silver Dragon can treat itself as though it were wearing or wielding any specific magic item in its hoard. It must get a full night's rest in its hoard at least once a week to retain these benefits.

Etc, etc.