Quality of Equipment (DMG)

Most of the equipment a character buys is assumed to be of average quality—neither too cheaply made nor too elaborate. Thus, weapons are serviceable with stout hafts and sturdy blades. The metal is not so poorly tempered as to make the blade hopelessly brittle. The blade is not elaborately etched and the hilt is not encrusted with gold. Other items are of everyday make, usefulness and function superseding artistic needs.
However, quality can vary from item to item. For some items it is important to know the quality, since this affects a game ability. The three items where quality is most significant are locks, horses, and weapons. In other instances, quality becomes important only if you or one of your players wants an item of exceptional beauty or of exceptionally shoddy construction.
==Lock Quality==
The quality of a lock can increase, decrease, or leave unchanged a thief's chance of picking that lock. The higher the quality of the lock, the harder it is for the thief to pick. Table 24 lists the different lock qualities and the amount they add or subtract from a thief's percentage chance to open it. Unless otherwise noted, assume that all locks are of good quality.
 Table 24: Lock Quality
Quality 	Modification
Wretched 	+30%
Poor 	+15%
Good 	0%
Excellent	-20%
Superior 	-40%
Masterful	-60%
The quality of a lock cannot be discerned just by looking at it. Indeed, one of the tricks of the master craftsman is to disguise the difficulty of the lock by housing it in a cheap-looking case. A thief can learn the quality of a lock by attempting to pick it. This attempt need not be successful ("Gee, this lock must be a really superior job. It's a lot harder than it looks.")