I agree with the post above. I've seen a lot of other yuki's and most of them are afraid to get hit even though we have so many flinches.
Here's my build: Lunia Skill Calculator(JP)
The reasons why I left RB meteor as 1 is for flinching purposes, the reason why I didn't want to max is that its ridiculously long cool down. Sure it has a wide aoe range, but 1 minute cool down is too much.
Ice dragon heart is one of the best skills of yuki, sure it can be half of the damage of the RB one but its cool down is much better than the other skills such as pillar and cold blue dragon. There is a bug where you get really close to a monster, its initial damage will do a lot of damage.
If you are planning to Myth, Ice arrow is not the best choice. It will only hit one monster for every 15 seconds plus its cast time. Not very important in my opinion.
Having one on cold nuclear does not make a difference if you have zero. Maxing it would be a waste of skill points as well since it has a very long cool down which gives you a max of 2.2 seconds.
Why do I have elemental of freezing at only 6 and why not max? I found out that if you go very far away from a single monster and cast elemental where it would hit, the freezing time between shots are enough so the monster cant move at all. I have another reason why but it would be hard to explain unless I show it on video.
Anyways, you should have 1 on all flinch skills if you are planning on Mything all the time.
Also, all your skills are magic so the skill: magic blow is very useful.
In myth, I am always the person who lures, I love luring and doing the first huge damage on the mobs even there is a sieg. The fastest way to kill a mob is when they are all bunch of together, therefore the best class baits are the ones that can go through the mob (Tia and Yuki) anyways there are other characters that are good with luring but that would be off-topic. If you want to learn how I play yuki, I would gladly teach you in game, words alone wont help you.