>On more serious note, much of it sucks.
>We already have 'wield' that always wields weapon in mainhand
>and 'dual' that always wields weapon in offhand. Thus, these
>options are redundant.

You've missed first sentence from my post. I'm talking about logical metacommands, not about exact syntax for their implementation.
In practice you can map "primary" as "wield" and "offhand" as "dual".
You will have to remember as much as you have now. You still we be working with two commands for wield. (In very rare cases with the third command "both").

>Weapons that require two hands automatically removes offhand
>item. Personally, I think that's fine as is.

"both" command is here only for giants and two-handed weapons.
How in the current system you can wield a two-handed sword as a giant exactly as two-handed?
In my system "primary sword" wields it as one-handed and "both sword" wields it as two-handed. For other races primary and both for two-handed weapons will be synonyms. In fact, "both" command will be very rare and all races except giants may not use it at all. However, if you can better ideas how to avoid additional "both" command (or whatever syntax it will be mapped off) present it.

>In short, you want throwdown to inventory. However, an
>additional remove command for emptying a slot could work. The
>syntax could be something like empty <bodypart>

Something like that. Remove <bodypart> command may be implemented and it will mostly cover these three remove subcommands. Exception is "remboth" which removes both weapons at once.