@Telinous: This is a full time earring for SAM, and will offer more accuracy than any other earring in the game (assuming you're using a Great Katana, and not a polearm) because of the Great Katana Skill +5. ;p
Best Samurai Earring Period. like Kouu has said it is a full time earring you'll generally never take it off. on a side not you can also now sell a triumph earring if you got one since this has exactly the same amount of Str. meaning its good for WS that have a Str mod on other jobs as well.
OK Orphanos has a perfectly valid point. Gil can't buy GK skill +5, which also has a hidden effect of Acc+ 4.5 and Att.+ 5. Which allows accuracy to be replaced in certain situations, such as Askar Korazin. Parrying is a definate plus. And obviously STR for WS mods. I digressed, lol. But Orphanos is correct, Money *can* buy STR +2, now even cheaper than triumph with introduction of flame. Dual wield is a rarity, not as rare anymore due to the new neckpiece "set" type thing but i don't know much about that to be perfectly honest. Also another little plus for samurai's around; this earring, capped and merited skill and a Justice Torque will allow samurai to use the new ws "Tachi: Ageha" at level 75(not sure why you'd want to though).