That 'brushed' stainless finish is probably the easiest to maintain and 'fix' for small scratches. A green Scotch-Brite pad usually works very well for that, rubbing in a linear direction to keep the fine lines of the factory finish looking uniform. Sometimes it's easiest just to lay the Scotch-Brite pad on a table/bench, and rub the knife over it.
If there are any other heavier scratches that won't quite be removed with the Scotch-Brite, some 400-600 grit wet/dry sandpaper should take care of those, used in the same manner (linear passes in-line with the factory finish). A softish sanding block, such as a rubber eraser, can be used to wrap the paper around; it'll evenly distribute pressure, which helps to keep the finish looking more uniform, especially over rounded surfaces.
I'd strongly suggest taping over the MOP (assuming mother-of-pearl) handles while working the stainless, so you don't needlessly scratch them or rub stainless swarf into them.
No guarantees about lessening or affecting the value of the knife, in fixing the scratches. Odds are, if the knife is truly a 'collectible', any work done to it will usually lessen the value. At this point, it's already 'blemished'. I'd just treat it as a user; but you should still be able to make it look near-new again, if you're careful about it.
