What does disarming mean here?

I wound read it as “the drug has less effect” - so in that case you can better abuse these drugs if you are worse at “disarming” them I guess

"Hard headed", "not a cheap date", "not a lightweight"? Hard to say if increased tolerance is good or bad (especially if we're uncertain about how addictiveness/susceptibility to addictive behavior it passed)

I would have thought the main armament that nicotine has is its addictiveness

perhaps "making less harmful to the body"? this could potentially be accomplished separately from making them less effective