2 questions I would have VERY late into the convo is
1) how come it is thought that you can't use emotional alomancy on an invested person? I don't remember any indication of that being impossible.
2) would it be possible for Kal to Lash a coin or Vin herself, for they would both be invested? It is impossible for one to Lash someone using Stormlight or wearing Shardplate, but also take into consideration that someone burning metal is way less Invest that someone Surgeabinding
Also, another thing not brought up is that the only 2 ways to kill a Surgebinder, is 1) a Shardblade or 2) (headcanon as balls) destroy his head. Vin could possibly pull it off with a duralumin pewter strike, tho if she whiffs it's a slap for Kalidin