In English it should be pronounced "JUST-i-KAR". Well, you could shift the emphasis around the word depending on your accent but the "c" is definitely hard.
If you wanted an authentic Latin pronunciation it'd be something like "YOOST-i-Kar" I think.
Although I'm not sure what a "justicar" actually is, "justiciar" is an antiquated word for a political office but it seems the scifi/fantasy crowd has appropriated the word, slightly misspelled "justicar". Kind of like how we got "paladin" from the Latin "palatinus" (high ranking official in the Roman Empire, later a high ranking knight/member of the nobility in medieval courts).
---------- Post added 2013-01-16 at 05:55 AM ----------
Didn't Blizz state it's officially pronounced "School-o-mance"? So you're all wrong...
If there's one thing World of Warcraft players hate more than people who don't play, it's people that do play but not as much as them.
Scholars are Schoolers now?