Too bad there isn't a way to increase your polearm reach beyond the standard 2 square reach...there isn't right? Cause that would be pretty awesome, lol.
Atm, I'm thinking the optimal way to build this character is to focus on axes early on, getting the Reaving Axe feats to inject more OA's on a regular basis--and knocking anything prone is a pretty sweet controller-like ability that would work beautifully with this 'mostly-striker' build. ASAP, she could get the Grounding Shot and Headman's chop feats to be able to hit prone targets normally as well as dealing +5 damage when she does, and she could get some of the mobility/opportunity attack feats like Agile Hunter(+2 to power-related shifts...will stack exceedingly nice with Nimble Strike and Battle-Scarred Vet/Ghostwalker Style), Blade Opportunist/Combat Reflexes, Defensive Mobility/Battle Caster Defense...there are so many options, I think this characters greatest weakness will be a shortage of feats...but she will have enough to have a very well-rounded style of combat.
Power-wise, I'm definitely getting Twin Strike and Nimble Strike(with the Seeker Hybrid, that means she'll have to be Human), then for her encounter/daily/utility choices she will focus on powers that slow/hinder foes, or provide other useful utility abilities, to take advantage of her mobile/ranged focus.
I'm still working on her in the Character Builder, but I'll post her sheet up here once I finish it.
As soon as the GM allows it (or should I say if....?), she can get a pair of throwing Khopesh with the Farbond Spellblade enchantment, which becomes available as early as lvl 2. Later on around lvl 11, she can pick up HBO then Deadly Axe and a few other critical attack-based feats too. HBO would let her use Twin Strike to fling her weapons around every time she got an OA, which would double her chance to crit and knock stuff down =]
---edit---
Might delay getting HBO, the Reaving Axe feats, and a few other feats till lvl 16ish, when her Seeker PP will let her actually perform ranged OA's... And I also can't seem to find any Seeker multiclass feats, are there any?