JUSTRIGHT, the integral refers to the bolster between handle and blade. What we westerners would call the guard. Integral means that it was forged as part of the blade and tang, or so well welded to it that blade, bolster, and tang have become a single piece.
You have to understand that this is something usually found made before 1950. Most khuks made in the last 50 years have thin sheet brass bolsters and caps soldered together that are filled with handle material and laha ( or himalayan epoxy a Uncle Bill used to call it ) a mixture of tree resin, beeswax and god knows what. Interestingly, if you add brick dust to the mixture, you end up with "cutler's cement" or so I'm told.
Part of the fascination with old, often Indian made khukuries, besides their military history, is that many are Panna Butta style, in that they have a full tang with scales on each side that are "riveted through" ( panna butta in Nepali ).
The opposite is the khuk that has a rat-tail tang either burned or drilled into the handle, and filled with laha. Those made by the local blacksmith or kami often end with the tang only partway through the handle. These eventually come loose and have to be rehandled. The HI khuks have a rat-tail that extends completely through the handle, goes through the brass buttcap and a separate smaller eye or diamond shaped keeper, and then is peened over to lock it in place. This allows excellent solidity while at the same time insulating the user's hand from vibration shock as opposed to the panna butta.
Short of running over the thing with a main battle tank ( and even there the question is what gets hurt - the khuk or the tank ) either method ( full tang or full peened over rat-tail ) is plenty tougth if well done.
One advantage of the panna butta is that the scales can be made of smaller material than needed for a rat-tail handle. This means white gold ( ivory ), stag, exotic horn, bone, or fancy woodcan be used to excite the innate greed of the buyer. As a rule our forumites are truly gentlemen except when they turn from Jeckyl to Hyde and become Great White Sharks on a feeding frenzy. Watch for an UBDOTD ( Uncle Bill's Deal Of The Day ) and you'll see what I mean.