This pint-sized Paladin provides potential protection in a petite package.
Don't let size fool you! This is a useful fellow to have at your side. He's picky about who he fights for and with, though. He'll only fight for civilized warbands, and he won't play with Evil creatures. But then, what else do you expect from your standard, stuck-up paladin (no matter how big)? If your team meets his stringent standards, he's definitely worth looking at as an investment.
In the revised incarnation of the game, mobility has become the rule, not the exception. One surefire way to maximize a creature's activation is to move, then charge. This gives a creature double its base move plus an attack. The Halfling Paladin's hallmark ability is Charge Protection. This helps to negate that extended threat range and, in part, control the pace of battle. For that alone he's worth his points.
Now, Charge Protection is all well and good until you notice a small (get it?) flaw in this Paladin's perfect plan. It only protects his allies, not himself. This means positioning is key. You might want him to hang back a bit. Otherwise, you will find him base-to-base with the enemy's heaviest hitter. Of course, you could use him as bait in a trap …
As the likely target of more than a few charges, his combat stats are important. For his cost, the Halfling paladin has fairly average AC and Defense. Immune Fear is nice, but there are few fear effects in the game currently. His speed is only 5, so he likely won't be your farthest ranging piece, but that's not a bad thing. His hps are about 3:1 for his cost, which seems to be average to above-average for creatures with similar cost. It's enough to let the Paladin survive one or two blows from a core enemy hitter, anyway. He has a nice little (get it?) bonus tucked in under his basic attack -- Vindicating Blow. The bonus to hit is good but not great, so if you want him in combat, you want him hunting lower-cost pieces than himself. When he hits with Vindicating Blow, he can heal his allies or himself. With few pieces yet that can provide healing, this is a nice bonus. You just can't count on it hitting. Second Chance is another nice ability, but if you need a 20 to hit, odds are you're going to miss.
Synergies
In general, the Halfling Paladin helps all warbands that meet his high standards by virtue of his Charge Protection. There are, however, few pieces that really help him. Consider playing him in ranged warbands, where you don't want enemies charging your archers and spell casters. He's good for plugging a hole in the defenses, for a short time at least. Bodyguards are great for taking a blow for him, and creatures with the Defender ability are also useful, because you know where enemy creatures are going if they do charge.
500-Point Play
I can see the Halfling Paladin being a perfect fit in a 500-point warband because he has a big impact on enemy positioning for only a small (get it?) investment. However, given his propensity for being the target of charges, I wouldn't expect him to survive long. He might … just don't count on it.