Because the assassin has access to the Ki focus, enchantment is left to the ki meaning your only selection is in the weapon die and properties you'd like it to have.
Things you should be thinking about
- Weapon die size: how big of a punch do you want to pack, and what is it going to cost you to pack that big of a punch?
- Weapon proficiency Bonus: How much of an impact with taking a +2 weapon over a +3 weapon make on your accuracy (do the DPR calculations and figure it out, don't leave this to hypotheticals).
- Feat/Power support: While a lot of your feat support should focus on the ki focus, if you've got some specific things in mind for a specific weapon group then you should choose weapons in that group.
- Variety: You probably have the ability to quickly switch weapons, maybe you want that Glaive for reach, but sometimes need the accuracy of the rapier or the punch of the flail. This is the kind of versatility granted by a ki focus, take advantage of it.
- Story/Character reasons: think about your character, what kind of weapon do you picture him with? Is he the type to be bristling with blades and weaponry? or is he more subtle and favor easily concealed weapons? Does it change from battle to battle? This is probably the major source of your weapon choices (since most of your special stuff is driven by your ki focus).
By default as an assassin you get access to
- Military heavy and light blades
- Simple one-handed melee
- Simple ranged
There is a pretty extensive list of weapons here, particularly in the heavy and light blades (rapier, falchion, broadsword, glaive, longsword, greatsword). I'd start with grabbing a couple from this list (definitely rapier/long sword and probably a glaive, maybe a greatsword just to have a nice punchy option). Then grab an item or two off the simple one handed melee list, although most of the options are trumped by heavy blade options, however if you've got a story or feat/power issue that would provide a good reason to take something off the simple one handed-melee list, go for it.
Basically, the things you need to do are stack to-hit, damage, and things that boost charges.
Roughly at L10 you should have the following
- Rageblood class feature (might as well get access to Swift Charge)
- L1 At-Will Howling Strike (can be used on a charge, extra damage at-will)
- L1 Feat Two handed weapon expertise (feat tax, extra damage on charge)
- L2 Feat weapon proficiency Gouge (barbs should have nice toys)
- L4 Feat MC Fighter/Rogue (opens surprising charge shenanigans)
- L6 Feat Surprising Charge (1[W] on charge with CA? I'll take that)
- L8 Feat Weapon Focus Spear/Axe (extra damage on spear attacks)
- L10 Feat Powerful Charge/Deadly Rage (you decide, both probably merit inclusion on an exclusively damage oriented build, either way, MOAR damage)
As far as equipment goes, there are two essential pieces for the heroic barbarian.
- Horned Helm (extra d6 on a charge)
- Vanguard or Jagged Weapon (extra d8 on a charge for Vanguard, Jagged weapon for expanded crit range)
- Badge of the Berserker (doesn't promote damage, but goes a long way to making sure you can keep charging and stay alive)
- Boots of Adept Charging (again, doesn't boost your damage, but they keep you alive)
- Iron Armbands of Power (+2 melee damage)
Basically, your strategy with feats, powers and equipment are to stack damage.
Charge is your best move for many reasons, but the big reasons are the +1 to hit, and the fact that it's an easy way to stack gobs of damage.
With this character, at L10, with Powerful Charge and the Vanguard weapon, you're doing the following on a charge with CA (assuming Str 22):
To Hit: 2 + 6 + 5 + 2 + 1 + 1 + 2 = +19
Damage: 4d5+4 + 2d6 + d8 + 6 + 2 + 1 + 1 + 2 + 2 = 39.5 on average
On top of that you don't take OA's when charging, and you can shift a square afterwards. And while you're raging, your speed is 8.
Jagged vs Vanguard came up in the comments below and I should share the results of the math. For a +20 to hit on a charge, and +19 to hit on a MBA (both +3 weapons), the math is as follows:
Vanguard Howling: 4d5+4 + 2d6 + d8 + 6 + 2 + 1 + 1 + 2 + 3 = 40.5, 59
Jagged Howling: 4d5+4 + 2d6 + 6 + 2 + 1 + 1 + 2 + 3 = 36, 51
MBA: 2d5+4 + 3 + 2 + 1 = 15, 20
Crit damage:
3d8 = 13.5
ongoing 10 = 15
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Vanguard
.75 * 40.5 + .05 * (59 + 10.5 + .65 * 15 + .05 * (20 + 13.5) =
30.375 + .05 * (69.5 + 9.75 + 1.525) = 34.72
Jagged:
.70 * 36 + .1 * (51 + 15 + .6 * 15 + .1 * (20 + 15)) =
25.2 + .1 * ( 66 + 9 + 3.5) = 33.05
This gives the edge to the Vanguard weapon on the charge. However, in general, the Jagged weapon is the stronger weapon for the Barbarian as he wants the expanded critical to trigger Rampage. The Paragon tier feat Charging Rampage seals the deal on this as it allows rampage to become a charge attack which bumps the damage substantially.
Best Answer
I'll give a few of the best races with pros and cons.
Half-Orc (PHB)
Pros:
Cons:
Goliath (EEPC)
Pros:
Cons:
Orc (VGM)
Pros:
Cons:
Mountain Dwarf (PHB)
Pros:
Cons:
(Legend: PHB -> Player's Handbook, EEPC -> Elemental Evil Player's Companion, VGM -> Volo's Guide to Monsters)
There are other races that can work, but in terms of an optimal meshing of features and flavour, these four are the best of the best.