Err... Once again it depends on your build and play style. Since you're a lord knight I assume that you didn't go with full tanking capabilities (you would've been better off with Paladin if you wanted to tank) so I'll list out good offensive type cards. If you want to do high damage to players just get a weapon with a few slots like Glaive (3) if you want high base attack but thats in normal circumstances. Since you seem to have such powerful cards (like Thanatos) I assume you're on a high rate server so the little boost in attack most weapons give you won't be useful. I suggest just getting a weapon with 4 slots and slotting it with Hydras and then get another weapon with 3 Hydras and a Thanatos card for those people with high vit.
I normally don't like getting multiple weapons as it ruins the fun of trying to make the best weapon but w/e. If you want an overall good weapon I suggest getting a Doppleganger, Lord of Death, and maybe a Sword Gaurdian card if you have Bowling Bash. Thats just me though, I just don't like making a lot of weapons but rather a few really good ones.
If you give me more info on your stats and playing styles I can give you better suggestions though but if not I hope this little tidbit helped.
