Another option sounds better:
Make all controls customizable.
No, seriously, if we are using SNES-style controls, then look at the control scheme for A Link to the Past
Y was for items
B was for sword
A was for actions
and X was for maps
You can have the Arrow Keys follow that format for starters, and make modifications as you wish. Since the Sword and Shield will be moved to Space Bar and Shift, respectively, then B (Down) remains free.
And then what if there are conflicting "actions" that you want to have to toggle through? Like, in ALttP
, the Action button let you lift pots and grab and drag items, but they were also used for the Pegasus Boots if you weren't near something that could be grabbed, lifted, etc. Unless you make sure these conflicts don't exist (making the Pegasus Boots an item, using the aforementioned example), and/or eliminate "combo controls" (like pressing A and B with the Bombs and the Bow&Arrows equipped, like in Link's Awakening
, in order to shoot Bomb Arrows), you'll run into another problem with keyboards: the simultaneous character limit. Most keyboards have a buffer limit of 3 or 4 keys, which prevent any more buttons from being registered. Put simply, having more keys to use makes for trouble, because you'll likely have a player try to strafe diagonally while swiping a sword and performing some action (W + A + Space + Up), which gets really close to overloading that buffer. (On Windows machines, though, I believe that the utility keys "Ctrl", "Alt", and "Shift" are exceptions to that limit, but I'm not 100% sure on that.)
Sorry, I'm rambling. But these should be points for you to consider when adding/changing control schemes.