Also published on Bethesda's official site is the description of the second DLC:
New Terrain: Navigate the highs and lows of the steep canyon walls, caves, riverbeds, waterfalls and explore the lush landscapes and rugged terrain in beautiful and sprawling Zion Canyon.
New Perks and Weapons: Survive the wild with Tribal Wisdom or exact increased damage with Eye for Eye. Honest Hearts offers a host of new perks and weapons including the .45 Auto pistol, .45 Auto submachine gun, the Compliance Regulator, fire bombs, war clubs, and Yao Guai gauntlets.
And here are some new screenshots: