I'm going to rule it this way regardless for my campaigns, but I'm wondering if this logic fits RAW and isn't even really a "home rule" to begin with:

1. Armblade requires the use of a character's Bonus Action in order to draw or stow.
2. Dual Wielder allows a character can draw or stow two one-handed weapons.
3. Therefore a Warforged character with x2 Armblades and Dual Wielder can extend/retract both with a single Bonus Action.

Its a harsh cost to draw an Armblade regardless so its hardly game-breaking in any event, but I'm curious what folks' opinions are on the RAW of this.

The armblade talks about "retracting" and "extending" the weapon; the additional requirement of the bonus action to do so means that, RAW, this is not drawing or stowing a weapon and as such Dual Wielder doesn't interact with it in any way.

I personally would not even require the feat, however. If a character is already giving up TWO attunement slots for armblades, I'd happily let them pop both out with the same bonus action with no further investment.

RAW you can retract a armblade into your forearm or extend it from there as a bonus action. Dual Wielder is only useful to weapons that are drawn or stowed, not those manipulated in other fashion with specific action cost like armblades. As written the item interaction rules don't even apply to it, in the sense that you can't even use your action to do so, you absolutely have to use your bonus action to do so, which cannot be upgraded to an action instead.