This spell is a bit weak with a 2nd level slot though it scales with slots relatively well, consider. I think the best spell to compare this with is armor of agathys.

Armor if agathys prevents 5 instead if 1d6(average of 3.5) and deals 5 instead of 1d6 with a save(about 2.625 if they have a 50% to save). Both spells only deal damge if the enemy attacked in melee, but armor of agathys is a 1st level spell and your spell pushes foes 10ft. Also your spell has a duration of 1 minute instead of an hour and can be cast on allies.

So your spell protects less, deals less, lasts less time and uses a higher level slot, but it can be cast on allies and maybe pushes an enemy.

I’d suggest making the spell 1st level or increasing the damage reduction to 2d10. Also i suggest granting temp hp instead of danage reduction for simplicity.