A discreet attaché case, allows smuggling of weapons, tools, documents, and theoretically -- clothes. Additionally it has a number of 'built in' goodies. One might suggest that it would make a "nasty little Christmas present," if one were marketing a toy to baby-boomers for the Christmas season of 1964.
Goodies include 50 Gold Sovereigns, collapsible sniper rifle (with infrared sight and ammunition), tear gas canister (disguised as talcum powder), and throwing knife.
The tear gas canister is especially interesting as it explodes if the case is opened improperly, momentarily blinding the victim.
Bond tries to buy off Grant with gold coins, in the process stunning him with the tear gas. This gives 007 the opening he needs to fight Grant. Bond later wounds Grant with the knife, turning the tables in their final showdown.
One way, or another, I'm gonna find ya...