How to handle a weirdly unoptimized character?

[Vhaidara]

assassins and especially wizards have no business investing into Charisma enough to be anywhere near you on stat+5 for trained+half a level basis alone. (Of course, it's a different story if they're half-elves and took feats to boost their Diplomacy)

Agree on the rest of it, but Cha secondary is actually standard for Night Stalker assassins, and Tiefling Wizards can do Int/Cha pretty effectively (Imperious Majesty fixes init, and wizard doesn't really need a secondary). I had a tielfing enchanter/illusionist whose untrained bluff was her best skill because +4 class, +2 race, +2 theme.

Otherwise, I mostly need to echo what's been said: 4e doesn't assume or work particularly well with rolled stats, dice rolls matter a LOT, especially at lower levels, magic items and expertise feats aren't really optional.