The confusing nature of 246/256 skill capFollow

I've only taken SCH to Lv37 for a SJ, however I'm confused by something. I was under the impression that Dark or Light arts boosted your respective skill to B+ thus a 256 rating. Now I noticed that my RDM which has a native skill of 230 elemental goes up to 256 just like SCH main. However, my DRK skill is 200 unlike a SCH's 210 without arts. So is this why my Dark skill caps at 246 compared to 256 skill? I tried BLU/sch and noticed the same thing with healing skill. It's like if you don't break the tier of D cap, you not able to reach B+.

Ok so I was right in my assumption. Now here's the real question. What if a RDM that normally has 200 Dark magic skill decided to dump 5 merits into it? That would lock them at 210, same as SCH. I'd assume that the new dark skill would be pushed to 256, right?

From what I've seen the boost received from dark/light arts falls into 3 different categories. It doesnt matter if your native skill comes form your main or your support job.

If your native skill is B+ or higher (256+) before using dark/light arts then it will not change after using dark/light arts.

If your native skill is anywhere between D through B+ (210-256) before using dark/light arts then it will be 256 after using dark/light arts.

If your native skill is anywhere below D (101 to 210,) before using dark/light arts then it will be 246 after using dark/light arts. 101 is the lowest you can have since /sch is gonna give you 101 in every magic skill.

Another thing I observed is that Gear and merits do not seem to count toward your native skill before using light/dark arts but is calculated after the boost received from those arts. I have 8/8 elemental merits which boosts my 75rdm elemental magic skill from 230 up to 246 (16 point difference). after using dark arts it was at 272, which is also 16 points higher then the 256 I should have without merits. This makes me believe that the game sees me as having 230 native skill then boosts it to 256 using dark arts then adds 16 more skill from my merits.

To test gear I still used my 75 rdm but checked on dark skill. Native dark magic on 75rdm is 200. I equipped glamour jupon (+3 skill) and crimson finger gauntlets (+10 skill) for a total of 213. After using dark arts I was at 259. I believe the game sees me as having 200 native skill then boosts it to 246 using dark arts then adds 13 more skill from gear.