1 - Ophidian Slayer Radiant Scimitar
2 - Hit Mana Leech
3 - Depends on the build
4 - SSI 30
5 - Damage Increase
3a - Hit Stamina Leech
3b - Hit Life Leech
3c - Hit Lower Defense (if not on glasses)
I don't know which Ophidians your fighting, you might enhance it with Bronze for additional fire damage, or with Verite for the poison damage.