I had some imbused Suit with heavy Mana focus
MI 8, MR2, Fire/Physical 70/70, Weapon Soul Seeker, with +10 Chv Sheild, inbused ring/bracelet, DCI 15, DI 22, HCI 15, 22% Fire resist, trying to kill some stronger Monster like Hiryu, Great Dragon, sometimes find it even hard to kill a KazeK as out of a sudden my HP just gone from 80% to 0, not too sure what kind of magic it had on me, I wonder how you guys managed to Solo those mini champ Boss, like Sty Dragon?? I can't even get to kill 2-3 Ninja at a time. So, what is the key here exactly? My swingspeed? My Stamina? Or related to a slayer weapon? What has it got to do with getting hit? I do have Vampire on, even, but, it doesnt seem to be making any different, I havent try cursed weapon with SS, it is also a must?
One obvious mistake is that you use a shield with bushido and parry. Drop that shield, i reduces you parry chance to 5%.
Also it seems you not have the best suit. At absolute minimum you would need around 150 stam, 30 mana, 90-100 di from items, as many hp you can get. Your 30hci/30dci are ok for now, but try to get more.
That soulseeker is not optimal today, for your setup i would suggest a radiant scimitar and a daisho imbued with 20ssi,max stam and mana leech,45-50 di and remaining points into hld.
You also should learn what perfection, confidence, evasion, lighting strike, momentum strike and counter attack do. These are the most important bushido abilities, learn to use them well, they can make a very big difference if used right.
Use honor on everything, use eoo when possible and turn it off when not needed.
Have keyboard macros for everything , if using a one-handed weapon take advantage of potions, even the cheap pots from npcs make a big difference .
Your primary goal as sampire is to do enough damage to stay alive. That means you need to keep hitting your opponent and not droppping swingspeed to much after taking damage.
Always watch your stamina, if it drops to low use a refresh pot or divine fury.
Do not worry about greater dragons or hiryus now. Especially hiryus can be extremly nasty , they can kill even a well equipped sampire in 2 lucky hits if you have all odds against you.
When fighting things that do heavy damage with physical attacks, use an armored swamp dragon for damage reduction and possibly feint with the daisho.
Also have a look here
http://uo.stratics.com/content/arms-armor/combat.php
You do not really need curse weapon for most things, the 20% life leech you get from vampiric embrace is enough in most cases.