(The whole Druchii thing makes you very good at grovelling, had you noticed that?)
The idea behind the halfbreed thing is that he's only used as a noble for border patrols; the fluff is based around the idea that he's more or less a pet of his father and so other druchii don't pick a fight. He's generally stuck out in the hinterlands conducting raids on lizardmen; that and the fact that he's even more unpleasant than your general dark elf, so they tend to find him amusing.
In terms of the conversion, I gave him a plain sword simply to match what I usually arm him with in a game; one magic weapon, one extra hand weapon. That, and the fact that I thought another big magic blade might have been a bit over the top in 6th edition WFB. Not in 2nd or 3rd, mind you
