Okay so here's the solution:
Have Dreadfang in your swap set. Swap. Use Dreadfang. Swap back.
You've done it. Now you can use A2 Might Merc with Infinity so you don't need to worry about attack rating or getting Convicted ever again.
Trust me when I say that there is no world in which that Dreadfang Bash Merc is beneficial to your clearspeed outside of being a novelty toy. It's not even about making your Merc optimal. If A5 Frenzy Merc could use Last Wish + Dreadfang I'd be all about it, but right now you're giving up all the perks of A2 merc for virtually nothing you couldn't do yourself with a simple swap.
Again respect. You clearly play Barb and understand my build.
It would honestly be a pain to constantly swap to Dreadfang, proc Amp, then swap back just to start Whirling. On paper that sounds efficient, but in practice it breaks the flow. I like being able to tele stomp a pack or a boss, let the merc apply Amp naturally, and while that’s happening I’m dropping Grim Wards and Whirling immediately. No extra steps.
Also keep in mind I’m a pure hork barb. My goal is godly rares and gold for gambling. On swap I run dual Alibabas, one Ist’d and one Lem’d, which pushes me to around 500 MF and 1000 GF. That’s pretty optimal for maximizing hork value. If I stick Dreadfang on swap, I lose a big chunk of MF and GF. You can argue 250 MF is enough, but I enjoy squeezing every bit of value out of corpses.
My stats right now are pretty optimal for this stage of ladder. Once Last Wish becomes affordable, I’ll run one myself and gain the Might aura directly, plus more MF, Crushing Blow, Life Tap, and all the other utility on my kill side. I run Last Wish on non ladder and it’s insane for TZ hunting. Especially versus thorn Harolds, where Amp and Life Tap alternate. You chunk their life with Amp, then Life Tap procs and your life shoots back up. It’s a strong cycle.
So for me it’s about maintaining farming efficiency and flow. Merc applies Amp passively, I focus on positioning and horking, and later I layer in Last Wish on my own setup once it makes economic sense.