[Kaleban]

There's a point at which Thief skills really don't get any better, and that's around 150%, as the penalties in the game usually add up to no more than 65%, so you'll still have an effective rating of about 85%.

Plus, some of his skills are useless. Detect Illusion? I've found it quite useless, and some people have reported a 200% DI not puuling people out of Invisibility, so assign points here at your own risk. Set Traps? You get these as abilities, so I'm not sure on the interaction between the Set Traps skill percentage and the actual Set Traps ability. Move Silently is questionable as well, I don't think the game checks for this, as an Invisible Wizard cannot be heard either, so MS may be useless. Pretty much the only skills you need to worry about are Hide in Shadows, Pick Locks, Find Traps, and Pick Pockets. And at even 15% per level, with a high dexterity and other bonuses (add in equipment and potions of Master Thievery) you don't really need to worry about your primary skills as you'll have enough points to distribute.

Remember, an Assassin is all about the most efficient method of killing, and they do well at it. If my analysis above is flawed or incorrect, feel free to correct me.