Assuming you're going to focus on Whirling Slayer attack powers:
Keep in mind that, unlike two-blade Rangers, Whirling Slayers don't actually make attacks with their secondary weapon, and you rarely do more than 1[W] with any single strike. Jack up your attack bonus on the main hand so you hit as often as possible, and put a high-damage weapon in your offhand. This is especially important because your offhand damage does not typically include your Strength Modifier.
Consider using a
|+1 enhancement (Level 3 item, 680gp), +1d6 per plus on crit |
Power (At-Will): Minor Action. Split the weapon into two
identical weapons, one in your primary hand and one in
your off-hand. You can spend another minor action to
recombine the weapons into one. If you have the Quick
Draw feat, you can split or recombine the weapon as a
. The enhancement applies to any one-handed melee weapon. This maximizes the use of your action economy, though at the cost of limiting you to a +1 weapon in your main hand. Combine this with Iron Armbands of Power (your Level 6 freebie item) to get the most damage out of each weapon. Depending on your ability array, you may want to chuck Swift Slayer in favor of Quick Draw. You can always pick up Swift Slayer at Level 8.
Alternately, stick with a +2 waraxe in your main hand and use a
|There's not much point in having an offhand weapon that does something nasty "on hit", because you technically never actually hit with your offhand weapon. It just does damage. |
+1 waraxe in your offhand. You'll hit more often, and your offhand damage will be the same as above. However, you'll need TWO minor actions to draw your weapons ... and Whirling Slayer powers require you to be wielding two weapons before you can attack. Again: consider dropping Swift Slayer in favor of Quick Draw. You don't have much else to use Minor Actions on, so you won't lose much here ... but sacrificing your Move Action to get your other weapon ready effectively takes you out of combat for the first round. You're truly screwed in a surprise situation.
From there, get the best armor you can squeeze in. You'll have better armor with the Paired Waraxe option, since that is actually cheaper than two +1 weapons. Buying two +1 items for 680gp (total) leaves your Level 7 freebie slot open for +2 armor.
I'm assuming you'll use your Level 6 freebie for Iron Armbands of Power. The bonus here applies to weapon damage rolls ... so the +2 bonus applies to both main hand and offhand weapon damage.
Pick up a pair of Acrobat Boots. Nothing sucks harder than burning your Move Action standing up.
A +1 neck slot item of your choice.
One final note that has nothing to do with gear:
Half-orc seems to be a good racial choice for Whirling Slayers because the racial ability scores line up ... but you spend a lot of time shifting. Difficult Terrain will make you hate life. If you haven't already, consider going with an Elf. Wild Step + Whirling Slayer = gotta Immobilize you to slow you down.