When wielding a two-handed weapon, your Obliterate deals 40% more damage, and all melee attacks deal an additional 30% damage.
Might of the Frozen Wastes is a passive death knight ability learned at level 74 for death knights with the frost specialization.
0500Patch 5.4.0 (10-Sep-2013) Might of the Frozen Wastes now increases all melee attack damage by 30% (up from 20%).
0500Patch 5.2.0 (5-Mar-2013): Might of the Frozen Wastes now increases melee damage by 15% (was 10%).
0500Patch 5.0.4 (28-August-2012): Updated; changed from When wielding a two-handed weapon, your melee attacks deal an additional X% damage and your autoattacks have a Y% chance to generate 10 Runic Power.
0400Patch 4.2.0 (2011-06-28): Now increases two-handed weapon damage by 3/7/10%, down from 4/8/12%.
0400Patch 4.0.6 (8-Feb-2011): Now also increases all melee damage by 4/8/12% while wielding a two-handed weapon.