Hmm... Good thought, just something I will toss out for you to consider:
Army Banner - Swing 16/Thrust 16, Speed 72, Reach 247, No horseback; Price ~1000p
Ray (Spear) - Swing 21/Thrust 31, Speed 88, Reach 220, Horseback allowed; Price 8000p
Personally, I'd rather use Ray for the purpose you describe, its faster and more powerful with just 27 less reach. But once anything is over 200 reach, it functions well outside any enemy weapons. On field, as a spear, it is still devastating if you are good with timing thrusts on horseback - whereas the banner cannot be used on horseback. The only downside of Ray is that it is a tad expensive, but since you can buy infinite copies of it anyways, as long as you have the cash and uses polearms, it is a worthwhile investment.