When using a standard Scroll of Upgrade on a +N enchanted weapon, the weapon has a probability 1/N (1 if N=0) to keep its enchantment while becoming a +(N+1) weapon (still enchanted or not).
Consequently, using a standard Scroll of Upgrade:
a +0 or a +1 enchanted weapon will never lose its enchantment,
a +2 enchanted weapon has a 50% probability to lose its enchantment when becoming a +3 weapon,
a +3 enchanted weapon has a 66.66…% probability to lose its enchantment when becoming a +4 weapon,
作为一位 Warrior 你可以重铸你的已升级 Short sword in order to upgrade (+1) another melee weapon (这把短剑将会被摧毁).
You can safely upgrade an enchanted weapon by reforging an upgraded Short sword, the enchantment cannot be lost during that upgrade (but, in contrary to a Scroll of Weapon Upgrade, a new enchantment won’t be added to a non-enchanted weapon).
As a Mage you can disenchant your upgradedWand of Magic Missile in order to upgrade (+1) another wand (the Wand of Magic Missile will be destroyed).
If you plan to later reforge/disenchant your Short sword/Wand of Magic Missile, do not upgrade it above +1, as the melee weapon/wand you upgrade this way will only gain +1, and the additional levels of upgrade will be wasted.