User blog comment:Willbachbakal/Co-Op Plasmids: Presto/@comment-3567720-20110805091210/@comment-1330314-20110806032727

I apologize for the confusion I may have caused, but now that I've explained to you at length how my Plasmid works, it may be better for you to accept it as such. If you really do want to get into petty detail a la BioShock123, I never specified that Jet Spray or Solid Fuel came directly out of your hand, simply that it came out of the general location where your hand was. Nonetheless, it makes absolutely no difference, both from a lore and a gameplay standpoint.

To answer your second question: because it doesn't. There are literally millions of different things you could summon with a conjuring Plasmid, but I chose the above because I wanted Presto to be a combo Plasmid, i.e. something that made your other attacks more powerful. Your example of auto-attacking swords, apart from having more to do with World of Warcraft than the BioShock canon, would give it direct-damage capabilities, which isn't what I'm aiming for here.