Mind does nothing for gladiator/paladin. Until we have weapons with magic damage on them, we won't heal for any amount worth bothering with. Dex is also worthless as you need large amounts to hit the next tier of parry. Str adds a very small amount of damage, but with the mitigation part, it also requires a large amount to hit the next tier, although not nearly as much as dex. Vit gives you the most reward per point with more hp, more hp regen, better stoneskin, more from cooldown buffs, more magic damage mitigation, etc. So your only choices will be Str and Vit with Vit edging out Str. Now that's not to say you can't dump all 30 into Str and it will be a waste. It's only 30 points and at 50 that's not a huge difference. Just don't ever put them into dex and definitely don't put them into mind, that will be a complete waste of points.