There are various weapon enchants available in the World of Warcraft game. The benefit of using some of them - such as +5 weapon damage, +15 strength and +15 agility - can easily be determined straight from the description of the enchant. However, some end-game enchants are vaguely described. For example, consider the description for the Lifestealing enchant:
Permanently enchant a melee weapon to often steal life from the enemy and give it to the wielder.
There's no information on how much life it steals, how much it heals and how often it happens. The aim of this document is to answer these questions and to show the combat logs if you would like to verify the conclusions presented here.
You hit Nightbane ..and
Your Sinister Strike crits Nightbane ...
This test was done with a level 39 rogue holding a Black Menace dagger enchanted with lifestealing in the main hand fighting monsters in Duskwood. None of the rogue's special attacks were used during the fights. The auto-attack logs are available in Appendix A and the following are the observations:
A discussion that goes hand in hand with many weapon enchants is if it's possible to get them proc more frequently (increase the number of procs per unit of time) by using instant strikes. The second test was done to shed some light on this, by letting the same level 39 rogue with the same weapon as the previous test also use Sinister Strike and Slice and Dice. Sinister Strike is an instant strike and Slice and Dice improve the attack speed by 20% so the rogue will strike more frequently than with auto-attack alone. The logs from this test are available in Appendix B. The following observations can be made from the logs:
During the first test with auto-attack lifestealer proc on a 4.5 times per minute on average, while 8.1 times per minute when using Sinister Strike and Slice and Dice. Clearly the wielder can benefit from instant strikes and talents that increase the attack speed.
Lifestealer's chance on hit for the 1.50 speed dagger can be approximated to 11.8% by dividing the total number of procs (64 + 131) by the total number of hits (578 + 1063).
Lifestealing can also proc from other instant strikes, such as Gouge. See the combat log in Appendix D.
How often will Lifestealing proc from faster or slower weapons? The third test has the same precondition as the first test, that is, a level 39 rogue fighting with auto-attack only, but now holding an Ardent Custodian enchanted with lifestealing. The combat logs for test 3 is available in Appendix C.
Apparently slower weapons with Lifestealing are assigned a higher chance to proc on each hit. Indeed it makes sense that Blizzard makes this adjustment. If not, who would put lifestealing on a really slow weapon? Assuming that Lifestealer's chance on hit for any weapon speed is calculated by multiplying the weapons speed with a constant, and that the 11.8% chance on hit for the 1.5 speed dagger is accurate the following generalized formula can be deduced:
Chance on hit (%) = weapon speed * 7.87
For example, a 1.5 speed weapon would be assigned a 11.8% chance on hit. A 3.5 speed weapon is assigned a 27.5% chance on hit.
It should go without saying, but the inner workings of the World of Warcraft game are of course unknown to me. The formula presented above is a theory and not based on input from Blizzard. Another issue that require a remark is that the sample size of 1641 hits used to deduce the formula does not offer a very high level of confidence. See the formula as an approximation.
The reagents for the Lifestealing enchant are 6 Large Brilliant Shards, 6 Essences of Undeath and 6 Living Essences. Their median sell prices are respectively 6, 4 and 10 gold, according to the data available at Allakhazam.com on the 26 of April 2006. So the expected price would probably be around 120 gold plus the enchanter's fee. I paid approximately 96 gold for the reagents and the enchanter charged 10 gold on the Dentarg realm.