How kind of you! most suggestions below are sensible, but I disagree with wireless usb presenter - this is almost definitely already available from the office IT department, so redundant to give as a gift.
Personally, the thing that makes nost difference to my life as a consultant is a nice, light carry-on luggage, ideally with 4 wheels so you can drag it alongside you vs behind you. Suitcase should also have a good place to put folded shirts. In a perfect world, suitcase would also have a place to put folded suits, in case your brother doesn't like travelling already suited up (definitely a thing for long-haul flights).
Depending on your budget, a nice add-on gift is a laptop bag / briefcase with a strap that can be put around the handle of the carry on luggage. This makes travelling even lighter and easier, especially when waiting in line at security or walking through the airport! - see what I mean here https://www.everki.com/products1/briefcases/flight-checkpoint-friendly-laptop-bag-briefcase-fits-up-to-16-detail