1) An act affirming an oath could be what is invoking the focus. Which is to say when one makes an oath to protect couldn't protecting others through deed be like thinking a command? I don't think we've ever seen characters using powers not in fulfillment to some oath thy have made. (Except maybe Jasnah, though she only uses her powers to save others, could be why she brought Shallan along to the alley)
2) Poorly made eons create low power effects, poorly mixed metals can be ineffective or dangerous, poorly worded oaths only give a sliver of the power of the proper Oaths.
3) Kaladin makes all sorts of oaths, save Tien, Protect the newbies, Help the bridgemen survive, these poorly worded oaths allow him to build a bridge with Syl who seems to be his spiritual connection to Honor's power, however not until he makes the Oath does he get full access see point 2.
All the other characters who surgebind have at least an oath (except maybe Jasnah we don't know too much about her personal life yet). Kaladin makes a ton of smaller deeply held oaths, as mentioned before, Shallan makes some sort of a trade or pact with a... what are the inhabitants of Shadesmar called? Shades? In additon to her oaths to save her family and become Jasnah's ward (These are getting a little loose with the defintion of oath). Dalinar asserts that he will NOT LET ELKOHAR DIE before impossibly stopping the chasmfiend's claw while his Plate glows and we later find out that Elkohar's gems were partially drained, yeah Dalinar's a surgebinder (he also gets Thrills, a possible parallel with Shallan's Memories). Szeth has his Oathstone and the Oath to go with that.
The only real candidates for the focus on Roshar seem to be spren and oaths, not all of these characters have a spren however, that seems to only be Kaladin. You could say that the Shade? is Shallan's "spren" and Jasnah may have one as well, but well nothing like that exists for Szeth or Dalinar as far as we have seen (Dalinar's may be immature like when Syl was "like other windspren"). Oh I have seen the suggestion that the wavelengths of stormlight are the focus, which could be true but that seems to be an effect, the color of stormlight you absorb doesn't matter it's just what the powers effects put out that remains consistent.
Really Shallan and Jasnah are my weak point here but I think that's mostly because I haven't re read the parts where they used their powers in quite some time so I'm fuzzy on the details there.
Thank you for reading my ramblings on the subject, oh and I'm relativly new here has anyone else suggested that Dalinar is a surgebinder? My search came up with no results for that combo.
