I don't understand how Sanji can keep fire on his leg without burning himself or at least the hairs on his legs x)
Also with raidsuit(wich can supposedly not be lit on fire as seen in WCI) is Sanji unable to use his diable jambe techniques?
Luffy's red hawk while cool looking never made sense to me either, if it was due to speed then why does is hawk gatling not a fire based attack.
If all of this is due to haki, Oda better explain haki properly like Kishimoto explained chakra in the begining of naruto and set limitations and drawbacks.
I personally don't like these kind if techniques or attacks too much myself. They almost make certain DF powers look pointless to acquire the fruit, somewhat..
ODA gives reasonable context and illustration to suspend your belief of an already fictional story. EX. Sanji's couldn't land a critical hit against Jabara because of his Tekkia, always minimized his damaged. So through high speed friction, he set his foot a blaze to burn into Jabara's defense. and with 2 hits he did so. Luffy's is similar but less believable; Using hardening haki, & a high speed punch to create friction on his fist for an fiery explosion.
I don't like these makeshift abilities that have similar effects to DF.. shockwaves, fiery attacks, ice attacks, etc...
But Sanji's DJ, is very believable for an attack. His hell memories is like am exaggerated gag attacks which im not mad at because it really is funny