That way, he was suffering from the 20% XP penalty prior to taking the barbarian level, and has had a 40% XP penalty since then. What are you thinking the rules are that adding a level of a third class would make the penalty go away rather than doubling it?Or that Belkar has one level in a secret third class. Ranger 14/Barb 1/??? 1
Given his stats, his options are limited. If he took 2 levels of Fighter, he'd get weapon specialization: slashing, and he certainly does a lot of slashing according to the sound effects. So maybe Ranger 13/Fighter 2/Barb 1.
That way, he was suffering from the XP penalty prior to taking the barbarian level, and has been in sync with the others since then.
(Also, weapon specialization: slashing? Weapon Specialization: Greatsword, which is what Roy has, requires four levels of fighter. There is no such thing as "weapon specialization: slashing." Smolder, you have very definite ideas about D&D that seem to be completely related to a different gaming system entirely.)