I buy 6mm - ¼” square drive sockets as I need them. A small set can be had quite cheaply but with tools it pays to buy the best you can afford.
The good thing about buying this way is you just buy what you need. Draper tools and Torx bits might not be up to full-on servicing/maintenance but on knives they will last a lifetime. Amazon UK sells two packs of individual Torx sizes that can be good for holding one screw while turning the other side - pivots etc. A ¼” sq drv to 6mm hex will be useful for using bits from screwdriver sets as well as purpose bought individual Torx/Allen/metric/imperial bits.
Bought over a few years, I still use Torx drivers as well as Allen keys and a well and often used set of swearwords - always useful for those difficult to loosen screws.