Huh I didn't know about that one, will give it a try.
Did a lot of tweaking for Crysis 1 all those years back when it was released but the later Cry-Engine builds mostly hid or restricted the console commands so I haven't kept very up to date with the available cvars though the online documentation they have for the SDK is pretty handy since it applies to most of the Cry-Engine games.
EDIT: g_hidearms doesn't seem to be doing anything, guessing that's something Arkane customized from the default classes or how it's called.
EDIT: r_drawnearfov and change from 4-byte to float works, should return a default value of 55 (vertical FOV) and then when switched to 2 it hides the arm model.
Not that I'm all that great with screenshots or explanations either for that matter but r_drawnearfov with a value of 2 and then a value of 125 just to better show it's effect.
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This is actually proving to be a very powerful feature being able to query and override commands like this although it's easy to cause the game to crash if you're not careful with their name and also their type or how to say.
EDIT: And as for actual cheats for those more interested in that the usual cvars like g_infiniteammo and ai_ignoreplayer seem to work in addition to the already listed ones for Neuro mods, flashlight power and god mode.
EDIT: ai_ignoreplayer while a valid cvar and while it can be toggled doesn't seem to stop the mimics and phantoms, they're just a bit unpredictable in their behavior.