I'm not sure which of Davies's books you have in mind, but many books in philosophy are what the author Alan Jacobs calls "guild books," that is, books that are written by scholars with other scholars in their own relatively small field as the primary audience.  In other words, many philosophers are not even trying to make their books intelligible to a beginner.  Instead, they presume that by the time you are reading their specialized work you have already learned the language.  I think the best way to proceed is to start with many of the excellent books (sometimes by the same authors) that are specifically intended for a wider audience.  The more argument-driven books of C. S. Lewis are a good place to start (e.g. Mere Christianity, Problem of Pain, Abolition of Man).  Peter Kreeft also comes to mind.

I would also recommend perseverance.  The only way to really gain fluency in a foreign language is to persevere through many many difficult hours at a low level of comprehension, simply letting the rhythms and word patterns sink in.  Philosophy has its own language, and some subdisciplines even have such specialized dialects that they are practically unintelligible to other philosophers (try going to a Heidegger conference).