From the dual wield skill line you can choose two morphs that heal you:
1. Bloodthirst (morph of Flurry). Last hit heals you for quite a lot (can reach over 5k). It's the main DW single target spammable skill so you'll constantly be healed while using it.
2. Blood Craze (morph of Twin Slashes) provides a small heal over time, of around 1-2k or so per second.