Does "Way of the Hundred Fists" generate more than one "on hit" effects?

Solution 1:

Way of the Hundred Fists consists of 3 attacks, which appear to be 1 hit, 5 fast hits, than 1 hit again.

The 5 fast hits counts as one hit for any on-hit effect.

For example, if you have 0 spirit and use the full Way of the Hundred Fists combo, you will have 18 spirit since it gives you 6 spirit per attack.

I also tested this with on-hit effects by removing all equipment except a weapon with an amethyst in it (which steals life on hit), and found that during the course of a combo, I'd only heal 3 times.

As for your other question about the Hands of Lightning rune, it appears you are getting 3 extra attacks with no damage decrease per attack. I played around with it a bit, and although the damage per hit fluctuated a bit, it seemed to average the same per hit both with and without the rune.

The three attacks each seem to do 1/3 of 140% weapon damage each, so your 5-hit combo is around 9.3% weapon damage per hit, which results in an extra 3 hits giving you another 28% damage.

Solution 2:

There is a difference between "attacks" and "hits". Way of the Hundred Fists is, in fact, comprised of 7 hits by default (Hands of Lightning can increase this to 10). The second attack is the one that generates multiple hits. The 140% damage is divided among the hits. Each attack can also hit multiple enemies In other words, if you are surrounded by multiple enemies, you can hit each of them 5 times with the normal skill. This can be observed by turning on damage numbers.

It does seem as though the property "Each Hit Adds +X Life" does only proc once per attack and is therefore misleading. Other "on hit" effects such as Slow or Chill on hit may proc on actual hits or on attacks.

The huge benefit is that each hit has a separate chance to crit. This makes Way of the Hundred Fists the prime skill to use in conjunction with Sweeping Wind (especially with Hands of Lightning) as it can help you to get max stacks very quickly.