First Phase of Trials
Test: Whacking crap with headbutt and helldive for about 20 minutes non-stop.
Observations: no critical strikes! (about 100-150 trials)
Conclusions: "wtf!?" right? On any other lvl75 job in the game I'd be sitting on a huge frequency of critical hits (like around 30% probably). Well needless to say I switched sub jobs to /THF so I could establish that the critical hit calculations were correct (which they were).
Second Trial:
Test: Using screwdriver and power attack(chance to critical w/ TP), this was basically just a ceremonial test to confirm that blue magic spells would not ever critical unless sneak attack or some other special ability like chain affinity was being used.
Observations: I've done about 150 of these, and have not observed a critical hit.
Concusions: It appears that a physical blue magic spell will never critical without assistance from an ability.
Third Trial
Test: using screwdriver and power attack with a few points of tp (like 50-150) to see if a WS would critical during chain affinity.
Observations: on the fourth or fifth trial (screwdriver) I scored a critical hit (for maximum damage to boot). Finally a positive result! (I've since done this a few more times to verify with both power attack and screwdriver)
Conclusions: A WS with the "tp increases chance of critical" description will have a chance to critical during chain affinity's duration.
Fourth Trial
Test: Now that I know a WS with a chance to critical with TP I went back to testing a normal WS (helldive, damage increases w/ tp) with the same TP ranges (50-150) to see if that would critical during chain affinity.
Observations: so far I'm 0/20... I'm going to keep doing this for another 25-30 trials if I can avoid getting bored... but it's not looking good so far.
Conclusions: It appears that a WS without any mention of critical hits in its description will not critical without the use of sneak attack/mighty strikes or some other ability which guarantees critical hits.
(I might do some tests with a single-hit club WS to see what my critical rate for a traditional WS is.)
Fifth Trial
Test: Using power attack and screwdriver w/ a dissector
Observations: No change in "highest" damage dealt (not expected either), and no criticals observed. I did at least 100 trials.
Conclusions: Dissector doesn't "add" the ability to critical to an WS which won't otherwise have a chance to critical. This is not to say that a dissector will not increase the chance to critical during chain affinity.