Ramirez is a highly talented water mage and he is the guy to take Dresden apart if there's ever a need because he's the Olympic fencer that'd be going up against Dresden the weightlifter and if Dresden tries to fence with him it's not gonna go well.
It's interesting the way that he worded it. "He is the guy to take Dresden apart
if there's ever a need". So I may be looking into this wrong but it almost sounds like he's saying that Carlos has been tapped by the Council to be the one to go after Harry. The "if there's ever a need" makes it sound like an in story statement rather than a Jim Butcher statement.
"he's the Olympic fencer that'd be going up against Dresden the weightlifter and if Dresden tries to fence with him it's not gonna go well". So this to me sounds like if Harry tried to square off with him in a purely magical contest. Harry has shown in multiple fights that he is a street fighter. A down and dirty type fighter... Does what he has to, to survive. When he used his fists and feet against He Who Walks Before, when he fought dirty against Fix, using iron. Using words to make Nicodemus so angry he messes up.
So yes I could see Carlos being a problem for Dresden, but I also see Dresden having more street smarts when it comes to fighting, and surviving. Carlos's particular style of magic matches up well in a fight vs Harry, but as the books have shown, magic is only part of winning.