Mystara: revising weapons and armor enchantment rules

The rules for enchanting weapons and armor presented in the GAZ3 The Principalities of Glantri1 and Rules Cyclopedia2 do their job fine for the most part. Once you get into some more costly and exotic items, however, the math begins to break down really fast. The issue with the default weapons and armor enchantment rulesFor example, if someone desires to enchant a tusked shield weapon, it will calculate its Initial Enchantment Cost as follows: the formula Price [gp] * Encumbrance [cn] * 5 becomes 200 * 275 * 5 = 275,000 — more than a quarter of a million gold pieces for a single +1 bonus! Compare this with a run-of-the-mill normal sword +1: 10 * 60 * 5 = 3,000 gold pieces. A similar problem becomes pertinent with the introduction of exotic classes. In Creature Crucible - PC1 - Tall Tales of the Wee Folk,3 we see the centaur bardings with the following stats: Type AC Cost Encumbrance Leather centaur barding 6 650 600 Chain centaur barding 4 1,300 1,200 Plate centaur barding 2 2,600…