Midori-chan
Swordies don't have as many skills, so personally I'd just make the change at 40, but if I was doing like, an acolyte or mage, job 50 is really the only option. x.x If you just want the bare minimum for peco and have hp regen for potting, j17.
Of course that's only 1 endure, no masteries, and lacking prereqs for second class.
If you're 2hsword knight? YYou'll want bowling bash, which means bash 10 and probably 2h mastery so now we're j41 and still no endure, and a weak provoke. Want to have a strong endure and good provoke (devestating on their defence) and you're j55...oops?
Spear knights can forgoe that sword mastery, which albeit making for a more painful swordsman life, let's you off at j44.
Of course if you' go crusader, you have no AoE other than suicide cross, so you might want magnum break too...but then you aren't needing 2h mastery but 1h mastery, so j61. Could skimp on bash but that added HIT from it, coupled with stun, make it superior to holy cross in some instances.
But of course there are also spear saders, so once again you can skimp on the masteries and just go j51.
Note the numbers are over j50? Right, can't do it, much less on j40.
Endure: positioning for gc/brandish/bb, and mobbing (yuck), prereq for peco
Provoke: tanking newbs, lowering defence on monsters like loli. Prereq for endure
1h/2h mastery: duh
HP Regen: healing self, better recovery from pots.
Bash: stun+increased accuracy, prereq for BB
Magnum: AoE for saders w/o GC, needed for BB
Hardly say they don't have many skills: to max all swordie skills takes j71. Now THIEF on the otherhand, with only 51 skill points in total, they can say 'not many skills'.