Luck has the effect of for 10 pts making it as if each of your skills is 4 pts higher. For example you pay the spell costs with level 25 illusion as if it is level 29. You don't get perks.

Fortify skill slows down leveling. For example if I have boots of fortify athletics +8 then my athletics skill which is 25 will have leveling as if it is 33. The reason is that at 33 there are more 'clicks' to reach the next level. For athletics I think a click is a second spent running. For blunt a 'click' is a connection with an opponent.

This is established by the wiki unless I am wrong (both those two things). The thing I wonder about that I couldn't see from the wiki is whether luck ALSO slows leveling down? I don't think so but I am not sure.

Fortifying skills does not slow down leveling. You level at the base rate even if fortified.

Note that this is fortifying. There are some skills that are enhanced by abilities vs fortifications (eg the skeleton key or Frostcrag alchemy lab) but those are exceptions.

So fortifying does not slow leveling. Luck increases do not slow leveling.

Thanks for that correction. The wiki says the same. Though it says when fortify is an ability it may be slowed. Not sure what it means for it to be an ability?

I think what the wiki is talking about is something like the skeleton key which fortifies Security by 40 points and does indeed slow the levelling of Security, although if you drop the key briefly you can then 'collect' your stored Security xp the next time you pick a lock. Similarly, the Mercantile boost reward for Dar-Ma's quest gives a fortify to Mercantile which stops the skill from levelling for awhile until it 'catches up'. But the skill fortification from high Luck or enchantments or temporary spell boosts of a skill does not slow levelling progress. Using a spell to decrease your skill level doesn't speed levelling either.

Mara

People in the Blade training thread are saying that a drain blade spell 2 seconds 100 will help you to train blade? Is that true? Thats why I thought fortify would slow it.

Yes, the training cost is based on the effective skill not the base skill.

So if you drain the skill down to zero you can get very cheap training.

Personally I avoid doing this, but it's just a personal choice. To me it doesn't make roleplay sense and might make training too easy, but again it is an in-game feature.

That is training as in the sense of buying a skillup from a trainer. It makes it cheaper.

Drain and fortify have noo effect on training in the sense of repeatedly using a skill to cause it to advance.

If you get the fortify skill effect from an enchantment, a potion, a spell, a power, or a lesser power it will not slow down leveling. But if you get it as an constant ability it will slow down leveling. Examples of constant abilities are the Skeleton Key's 40 point bonus and the bonus you get from the Grey Prince's quest.

I'd add that draining skills and paying for leveling afterwards simply fixes the horribly broken economy in the base game. The training costs are way too high based on the various economic statements by the NPCs in the game, not to mention the reality of what we see as far as the various trainers' lifestyles. 10 gold per training point is ludicrous and impossible to roleplay because it simply does not fit with the economic realities within the game world. Morrowind was much better in this regard, but this is only if you wish to roleplay.

Allthough the base rate does not drop fortify will consider the bonus add to be your level, at least I have found that.
So it will take a bit longer to level up a skill while fortified, as 5 to 25 to level is very quick but leveling 75+ is a lot slower imo but I could be wrong with this.