Let's see if I can get this done without a browser crash like the one that wiped my first attempt to answer part of your question when it was 90% done...
There's some odd mathematics involved when it comes to the chance to craft, the chance to craft exceptionally, and how talismans factor in...
The following examples are for most crafting skills, that use a 0.2% chance gain, per 0.1 skill gained. (a few skills gain 0.25%).
Blacksmithing typically starts items at 0.0% chance to make at the skill listed to make the item. Most other skills start most items at 50.0%.
Base chance to make-
1. Equal to the amount above, plus 0.2% per 0.1 skill over that amount.
2. Actually does progress over 100%, but is not displayed over that amount.
Examples:
a. A Smith item requires 60.0 skill to make. At 67.3 skill, it would be 14.6% chance of success.
b. A Tailor item requires 60.0 skill to make. It starts at 50% at 60 skill, so at 67.3 skill, it would be 64.6% chance to make.
c. At 85.0 skill the tailor item would be 100% chance of success, compared to 50.0% for the smith item.
d. At 90.0 skill, the tailor item would be effectively 110% chance of success, but displays only "100.0%". The amount over 100% is important, even if not displayed, as it factors into chances for skill gain, as well as the chance to make exceptional.
3. A talisman with a normal bonus, modifies the percentage, but will not raise a chance that is 0%, unless that 0.0% is at the exact skill level a Blacksmith needs to attempt to make that item. So, if one needs 60.0 skill to attempt an item, and has 59.9 skill, not even a +30% talisman will raise it over 0%, until it hits 60.0 skill, at which time the chance becomes the base + the talisman.
4. The normal bonus from a talisman has NO effect on enhancing, nor does it factor into the math for determining the chance to make an exceptional item.
5. The chance to gain on a skill remains possible as long as the chance to craft the item being made is less (without talisman) than the Power Scroll value the character has used for the skill in question. So, for most skills, once an item hits 100% chance of success, you can no longer gain while making it. However, for Tailoring and Smithing (and possibly Imbuing), a person that has used a 105 powerscroll can get gains on an item until it would be 105% chance of success (though gains would be slow), etc.
Exceptional Chance to make-
6. The chance to make an item exceptional is calculated as follows-
a. 95.0 skill and below: The chance to make normally, without talisman, minus 60. This uses the REAL chance to make, if the item has a displayed value, without talisman, of 100.0%. To use the example in 1.d. above, an item with an unmodified 110% chance to make it, at 90 skill, would be 50% chance of exceptional.
b. 95.1 to 100.0: Gets an additional +0.3% per 0.1 skill gained (for a 0.5% to 0.1 ratio), so that the chance to craft exceptionally gains more quickly than chance to craft. Continuing the above example, the item that is 100% chance to make at 85 skill, would be 120% to make at 95 skill, and 126% at 98 skill. Its chance to be exceptional at 98.0 skill would be
126%-60%+(30*0.3%) = 66%+9% = 75%
c. 100 skill & above, when applicable: the bonus from (b.) goes away, returning to a 0.2% per 0.1 ratio. The effective result is that the number subtracted goes from 60% to 45% (50*0.3%=15%; -60% + 15% = -45%).
7. Unlike the chance to normally craft, the chance to exceptionally craft is calculated even when the effective chance is below zero (and displayed as 9%). As a result, Exceptional Bonus talismans CAN raise a displayed 0% chance of exceptional to above 0%. Note that any normal crafting bonus does not apply.
Examples: A Tailor is at 62.5 skill, making the item from previous examples, that he can start making at 50.0% normally at 60 skill. He is normally 55% chance to make said item, which makes his unmodified chance to make exceptional as -5.0%
a. Wearing a talisman that gives ONLY a +24% bonus to craft exceptionally, he will be 55% to make an item, but now has a 19% chance to make it exceptionally.
b. If the talisman was +24% to both make, and make exceptional, his chance to make said item would be 79%, but he would STILL only be raised to a 19.0% chance of making exceptional, as the normal bonus does not factor into the exceptional calculation.
8. The exceptional chance appears to be just a check against the SAME number that is rolled for the chance to craft. As a result, the percentages can be misleading.
a. If they were rolled separately, and someone had an 75% chance to make, and 15% for exceptional, you'd expect to get 450 items in 600 attempts, with 67 or so of them of them (15% of 450) exceptional. But, that's not how it works, when the chance of normal success is under 100%.
b. How it does work, is that you end up with 450 items, but since both percentages are checked against the same roll, the chance of an item being made successfully is much different - you end up with 15%/75%, or 20% of the successes (about 90 items) being exceptional.
Reason:
If the success roll is over 75, nothing is made
If the success roll is over 15, but under 75, a normal item is made
If the success roll is 15 or less, an exceptional item is made.
That works out as 1 in 5 (4 in 20) successes as exceptional, not 3 in 20.
c. This can be further skewed by using a exceptional-only talisman, to the point where the example above, adding in a +30% talisman, would produce 270 of 450 successes (or 60% of all items successfully made) as exceptional, as 45%/75% = 60%.
