130 str with vesper cores is 319 attack while 140 str with rings is 336. You use 88 status points for 15 attack, less then 5% more damage.
If it's a pvp/woe LK you can get FB instead of using a str headgear and have more vit. If you're a frenzy LK you could use a chick hat for 10% more damage. If you're a mobber/tank you can get more vit. If you're a BB LK you can get more dex for cast time or agi for aspd.
Most the stuff I think are underrated have already been mentioned, all I can think is Flame Skull card. So many people go places without using their shields lot since they don't have the reduction card. A 5% chance to stun, stone curse, blind or curse an enemy can really help sometimes.
