Arcane Strike (Complete Warrior) .... A must have for a duskblade.
Power Attack .... When you can't make a full-attack in some reason, use True Strike as a swift action and convert all of your BAB into damage (use a two-handed weapon for doubling).
Spell Penetration & Greater Spell Penetration .... Most (all?) of the attack spells in duskblade spell list allows SR. At higher level campaign, you must expect that many of the monsters have SR which is hard to penetrate even with your spell power class feature.
Empower Spell .... Whether if you can apply metamagic feat without increasing required time when using Arcane Channeling is debatable. I say yes. But if your DM says no, also take Rapid Metamagic feat (Complete Mage). Empowered Vampiric Touch delivered through Arcane Channeling is nasty.
Energy Substitution : Acid (Complete Arcane) .... This helps a duskblade to deal with monsters with resistance/immunity. Polar Ray is a strong spell but useless against something immune to cold.
Close-Quarter Fighting (Complete Warrior) .... This feat is good for any melee combatants.
#I do not recommend those 3 feats in your list
Run .... Why you need this feat when your PC can use dimension door?
Practiced Spellcaster .... Doesn't do any good for a single class duskblade who already has CL = his HDs.
Battle Caster .... At level 18, you can simply buy a heavy armor made of mithral. A heavy armor made of mithral is a medium armor.