Another big mechanics difference between vanilla MM6 and MM7/8 is the recovery time calculation when using two weapons, one in each hand. Grayface patch for MM6 fixed this. So did Grayface also change the elemental ranged attacks?

You are correct about dual wileding. It was so slow to be completely non-fonctional in vanilla MM6. Plate and chain armor were also useless because mastering them never removed recovery time penalty as they should.

All of my elemental ranged attacks was actually tested with the Grayface patch, which I've been using exclusively since about 2007/2008 for all three games.
I haven't been using the last official version since the late 90s.

Grayface is great :)

Since we're talking about Grayface, he made another massive change to dual wileding in MM6 which *almost*
makes up for Armsmaster not being present in the game:
Wielding a sword or dagger in the left hand does NOT remove the damage bonus for using a mace/spear/axe.
It does remove the "attack bonus" you get from said axe/spear skill, (replaces it with Sword's, exclusively)
but that's quite OK, since using 2 weapons already
gives you a big bonus to "attack bonus" anyway from the weapon's own "+" bonus.

In MM7 and MM8 on the other hand, (still talking Grayface) using a spear+sword or axe+sword combo is not effective at all, since the sword/dagger being present removes the damage bonus from the spear/axe skill.
Still, dual swords is effective (no damage bonus to be had), also one sword+one dagger, or two daggers, are all effective combinations (the dagger GM damage bonus is never removed, as long as the dagger is wielded in the left hand).
If you wield a dagger in the right hand and sword in the left hand, the bonus is removed!
Al in all, I'm very pleased with the balance, since MM7/MM8 already have the Armsmaster skill which adds damage on top.

The Grayface patch I'm using is not up to date, though. Maybe he decided to change this formula in later patches...
Let me know if this is the case.

And now i also have finished MM7 in the merge with a new party of 4.
I was on a similar level at the end, but there was not as much of a feeling of being overpowered. The devils in the land of the giants with their meteors were surprisingly annoying. :D

Now i have an interesting realization...

I always liked MM7 better than MM6, with one exception: MM6's dungeons are way better.
Now that i played both in the merge, i will revise my opinion a bit: the thing that held MM6 down was it's magic system.

Playing them both in MM8 engine, with it's magic and skill system, i find MM6 the better game overall.
More zones, more enemies, more and better dungeons, all this makes MM6 better. The alignment choice in MM7 was an interesting new thing back in the day, but it's mostly an empty choice.