What Runes/ Gems to Use on My New Weapon

I've looted a Doom Prod Septum from

Duriel:

2H Damage: 23 to 41
Normal attack speed
+56% enhanced damage
+6 to max damage
+25 to Attack Rating
Prevent Monster Heal
Socketed 2

I'm thinking of using an

Amethyst for +80 attack rating and either a

Tal rune for +75 poison damage over 5 seconds or an

Eth rune (-25% target defense). I'm using a Javazon and this is a really good secondary weapon (shield &

Short Spear are my primary) so I want to make the most of it.

What do you guys think? Should I go for the big poison damage, or -25% target defense, or both and leave out the

Amethyst? I already have high attack rating. Any advice would be appreciated as always.

That's a low level weapon that you will outgrow pretty quickly, so my advice would be that you only use gems instead of runes to socket it. You can save runes to make useful cheap runewords such as Stealth, Lore, etc. If you find jewels, that's another option to socket into weapons, otherwise gems will do.