There are plenty of professionals that aren't that great with cards. MANY of them have very little skill at all. A good friend of mine calls himself a card guy and can't fan a deck, he also makes much more money performing magic than I do, so there's that.
I completely understand why the other esteemed magicians on this forum have been slow to define beginner or intermediate sleights. The biggest reason is that there really isn't just one standard. Someone like Shin Lim could be incredibly proficient at just a few moves and be considered the best out there, even when he might struggle with a pass or a bottom deal.
There's also the idea that however difficult the moves you use are, it doesn't really affect how magical the effect is. The impact is usually disconnected from the difficulty of the move.
Also, Christopher is 100% correct. Never assume that you are a master. The more I learn about magic the more I am blown away with the amount of stuff that I don't know. Just today, I learned 2 new versions of the magic square and yesterday I learned an amazing version using a birthdate. This is after studying the magic square for over 10 years and using 4 or 5 different versions in my act over the years. I got to the point where I kinda felt I knew every approach and this week I have been blown away! You always know less than you think you know.
That said, I will gladly put my reputation on the line and look like an idiot classifying sleigh of hand magic with cards.
I'll split up the move difficulty or the deception like this (all of this assumes some sort of proficiency with a deck of cards):
Self Working - The audience could do this, you just have to remember what to do.
Beginner - The magician has to be holding the cards and it can be passable in performance with a day or twos's worth of practice.
Intermediate - A sleight that's passable in performance with a week or up to a couple of month's worth of practice.
Advanced - Passable in a year or two.
Expert - A very specialized move that may take a few years to get down.
Master - Only able to be accomplished by a few people on the planet if anyone with any kind of consistency.
So, a self-working piece of deception (it's hard to call it a sleight) would be the Jay Ose false cut, the cross cut force, the cut deeper force or the Christ Force, and Flap Jacks by Paul Harris.
Beginner level stuff would include an overhand shuffle control, a one-handed fan, a card spring, a dribble, a shuffle with a bridge, a ribbon spread, possibly the glide, that move where you drop the deck and a card turns over, the through the fist move, the twirl change, and I think the slop shuffle would fit in here.
Intermediete magic moves would be the Elmsley count, the double turn over (depending on what version you do this might be higher), second deal, the Bertram pass, the turnover pass, the side steal, the slip cut, the riffle force, Houdini/Erdnase color change, shape shifter color change,
Advanced, the classic pass, classic force, bottom deal, the mercury card fold, a perfect faro, one handed shuffle with a bridge, diagonal palm shift.
Expert, the center deal, Ray's Rise, D'Amico's Second Deal, One handed Bottom deals, one-handed shuffle with a strip out, Erdnase Shift,
Master, anti faro, tabled riffle shuffle, memorizing a shuffled deck and using it in performance.
There's a ton of debate to be had over which moves should be where and then there's discussion about psychological principles like equivoque, and the trick that cannot be explained and how difficult some of these techniques are. The interesting thing here is that I think it's fairly easy to classify moves, despite the debate, it is much more difficult to classify the magician. I dabble in the advanced and expert category a lot but my Erdnase color change is pretty terrible. I haven't even mastered all the self-working stuff out there, how could I master the master stuff too? And, I have no idea what that makes me or how that classifies my level of skill.