And there's the way Luke detected the dark force around the tree and the way Luke knew Vader was on the star destroyer orbitting Endor and the way his line "I'm endangering the mission, I shouldn't have come" betrays his fear that his own power will be detected and give away the shuttle team...
I can see what Ush is saying, and mention of the force in every day language - in place of 'luck' or 'skill' as Ush said - was a good way of investing the force with influence and importance in the times after the Jedi, it gave it historic significance, made it 'culturally' relevant, etc., but I always assumed the force was detectable personally.
But that line from ObiWan, "If you strike me down..." is a far more interesting discussion point, and one that has intrigued me since 1977.
My prediction is that at some point Anakin will use the same line to ward ObiWan off trying to interfer with his journey to the dark side - kind of like saying, "The only thing stopping me killing ALL of the jedi is the fact some of them are friends of mine, but if you push me and try to stop me I won't let even that get in my way anymore"...
ObiWan probably throws that line in with one of two intentions: to taunt Vader by reminding him of his ambitions and drawing attantion to the fact that he is just a puppet of the Emperor OR to try and remind Anakin that they were once very close friends in the hope of luring him back to the side of good.
But we'll see, I guess...