Thank you all for your good advice.
I ended up deciding to go with the Protection tree. Hopefully it'll work out well.
As for the Plate armor: I'll certainly be on the look out for drops, though I did recently find a vendor of Plate Armor and Shields at Nethergarde Keep, the first such vendor I've encountered. Though I'll need to get to lvl 45 and earn a bit more gold to be able to wear that particular armor and shield (though some items only need a lvl 42), at least NK includes a flight point to which I can simply fly to when I'm ready for the armor if I can't first find the appropriate drops.
Now if I only I can find a stronger one-handed sword than the Mariner's Sword I currently have, as well as where glyphs can be obtained...
-G