Armory Arm + Colossal Fighter

This combo does not work. But not because of the reason you stated.

The new text for Armory Arm makes this clear. The key text is in the last sentence:

Once per turn, you can either: Target 1 monster on the field; equip this card to that target, OR: Unequip this card and Special Summon it in face-up Attack Position. While equipped by this effect, that target gains 1000 ATK. When that target destroys a monster by battle and sends it to the Graveyard: Inflict damage to your opponent equal to the ATK of the destroyed monster in the Graveyard.

You do not target the destroyed monster. The only thing that Armory Arm targets is the monster it equips to, and the effect itself does not target anything.
Instead, the key is that Armory Arm references the ATK of the monster "the destroyed monster in the Graveyard".

If your Colossal Fighter were to be destroyed by a monster equipped with your Armory Arm, and you chose to activate the effect of Colossal Fighter, the chain forms like this:
Chain Link 1: Armory Arm's damage-inflicting effect
Chain Link 2: Colossal Fighter's summoning effect
If Colossal Fighter revives himself, he's not there for Armory Arm to reference when Chain Link 1 resolves. So no damage.

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Kevin Tewart
KDE-US A. Director of Game Development & Marketing