24/15 and 18/21 will always be solid 2H builds.
24/15: 8 IF - 8 PS - 5 athletics - 2 Shield(?)
18/21: 3 IF - 6 PS - 7 athletics - 7 Weaponmaster
18/21: 6 IF - 6 PS - 7 athletics - 4 Shield(?)
Weapon master is best at 0 or at max, since it scales up at higher ranks. The higher agi build gets more use out of it, but you can just as well put ironflesh to 6 and have 4 points to put into shield or whatever else you desire. You can still use a shield with a 2H, just for gaining ground against archers, but there are always the 1 1/2 swords like the Two Handed / Bastard / Heavy Bastard / Longsword, which will act as a 1h in a pinch.
Genric mentioned throwing, which is absolutely viable. Just cut your ironflesh, or convert less. A completely balanced build, i.e. 18/18 is very powerful, as skills are more powerful than stats. Stats just allow you to raise skills to a greater extreme. You'll hit hard enough, you'll move fast enough, and you'll have 4 skills maxed at 6, and another at 5. 5 IF, 6 PS, 6 athletics, 6 Shield or Throwing, 6 Weaponmaster. You'll have 135ish 2H, and still have 100 wpf for throwing.
Stick to your gut feeling though, the claymore is awesome. The shield is just nice to have as an option. 24/15 Claymore warrior, you'll have a great time. If you realize you want the option to use ranged, crossbow demands 0 sacrifice towards your build - just gold and optional wpf (which I'd also recommend 100)