EDIT: The math is wrong. See later post for proper Vex numbers.

**How much are Vex and Graze really worth?**

Without Vex, you will make every attack at your base hit rate. I'll assume 60%.

If your average damage per hit is 10, then you're doing, on average, 6 damage per attack.

With advantage, 60% becomes 84% (a 40% increase). While advantage is up, you're doing 8.4 damage per attack.

How many attacks will Vex last?

With a 60% hit rate, it will take an average of 1.67 attacks to land the first hit. With an 84% hit rate, you will land an average of 4 attacks before you miss.

~~Total damage is 1 x 6 + 4 x 8.4 = 39.6 over 5.67 attacks, for an average of 7 damage per attack.~~

Long term gain, assuming you don't switch targets,~~ is thus +17%.~~

For comparison, Graze.

With just +3 Str on a 1d10 weapon, your normal average damage is 8.5. A 60% hit rate would thus give an overall damage per attack of 5.1. With Graze, you will also gain 40% of 3, or 1.2 average damage. That's a 24% increase in average damage. At +4 Str that increases to an average of +28%, and +5 Str gives an average of +32%.

Other riders on attack damage, such as Rage bonus damage or extra fire damage per attack, will reduce the value of Graze.

**Comparing again at 65%**:

Vex: Advantage is worth +35% damage. It will take 1.5 turns to land, and last an average of 5 attacks. ~~That's an overall damage increase of 19%.~~

Graze: +3/+4/+5 Str with a 1d10 weapon at 65% hit rate will give an average damage per attack of 5.525/6.175/6.825, while Graze will contribute 1.05/1.4/1.75. Gain is +19%/+23%/+26%.

**Comparing again at 70%**:

Vex: Advantage is worth +30% damage. It will 1.4 turns to land, and last an average of 7 attacks. ~~That's an overall damage increase of 20%~~.

Graze: +3/+4/+5 Str with a 1d10 weapon at 70% hit rate will give an average damage per attack of 5.95/6.65/7.35, while Graze will contribute 0.9/1.2/1.5. Gain is +15%/+18%/+20%.

**Summary**:

~~Broadly speaking, Vex and Graze are generating about the same average improvement to damage (somewhere around +20%). Graze becomes more valuable as accuracy drops, while Vex becomes slightly more valuable as accuracy increases. Graze also increases in value as your Str increases.~~

My new conclusion on Vex is that it's not overpowered, or even necessarily top-tier. My other math on Graze has led me to consider it a solid option when you don't have advantage, so now I'll consider Vex as being in the same mid-tier spot.