Do Green and Blue blades mean anything anymore?

[SirLiftaLot]

For sure, it'd be hilariously simple if your lightsaber crystal acts like a karmic mood ring:
Knight- "Master I'd like to study saber combat more extensively" Master- "sure my young apprentice, your blade is a brilliant blue I see no harm; in fact I saw this coming for some time"
3 years later after some rather risky missions
Knight- "Master why does the Council continue to order us on such tasks, it seems to endager us for less than positive outcomes. Many have been less than fortunate, and not returned with us"   Master- "Be mindful of these doubts my friend, the council has it's reasons" *sees blade has been purple in hue for some time*
2 more years pass...
Knight- "Master stay with me, please get up. Don't die here Master!" Master- "Remember there is no...ugh"
Blade shifts hard RED...
Knight- "None of you will get away with this, I'm twice the swordsman he was. He simply wanted to take you in alive for questioning, I have no desire to do such a thing. None of you deserve to leave here if my Master cannot!"

...Oh that would be a little hardcore of an early warning system for sure! Watching blades shift during battles or after trauma. A little too on the nose for sure.

But to the initial part of if you're well suited to be a Jedi, well once you construct a lightsaber you're well down the path to becoming a Jedi. So if you just make one and BAM out comes a red blade... I mean yeah that'd be a hard pass on the rest of your training for sure. "Master what does this mean, nobody has this color?" "It means your training is at an end, and not in a good way."

I feel like the idea that you get assigned a color based on your role/path as a Jedi and then can later change it makes sense to me from an in-universe and a lore perspective. It also means I can head-canon that Mace Windu DID actually just decide he wanted a purple lightsaber because he's Mace mother****ing Windu.

I can picture it now, a skilled and confident young Mace Windu tells the Council that he has constructed a new lightsaber, and ignites a purple blade. I could see Yoda commenting "a purple blade you have. Represent Vaapad, it does. Channeling darkness and fury of both your opponent and you into a blade of Guardian blue to make purple you are. A wise decision this is, Master Windu." Mace nods his head and thanks the Grandmaster, but in his head just says "I just like purple you old mother****er."

[DarthProdigal]

...yeah, you just get a point for that. I got nothing else I could possibly say.

[B-706]

they don't mean what they used to mean

[janx]

I've always reasoned that the "Jedi arts" line referred to the fact that the Sith order arose from a splinter faction of disillusioned Jedi, and while the Sith obviously have their own practices that distinguish them from Jedi, none of those abilities were on display during Maul's skirmish with Qui Gon.

As for the topic of blade colors, I believe each color still has a significance, although said significance has been changed or reassigned with the new canon.  For example, if I am not mistaken, formerly, yellow lightsaber blades were originally red before being purified.  That distinction has since been given to the white blades that Ashoka now wields.

it may have changed since Disney, but the Sith used to be a species.  Things get complicated, the religion spread to include other species and eventually the Sith Species got wiped out.

So it's not wholly correct that a bunch of jedi went bad and started the Sith order.  Though that version might be a bit simpler than "it's a people, but they died, and now other people call themselves that".

[Zren Tobas]

I know different but its like with Dragon Ball Z to Super, power levels really mean nothing anymore I know kind of an odd comparison but same idea