Some other ideas...
1) Clerics, in 5e, aren't your traditional mace-wielding heal-bots from earlier editions (or how they're portrayed in some other RPGs/CRPGs). Some domains provide proficiency in heavy armor and martial weapons, which allows you to go the plate-and-sword route. Even if your DM doesn't allow the Death domain (optional, from the DMG), you could likely achieve everything you want from going the War domain. Take some of the nastier spells as your prepared options: bane, inflict wounds, blindness/deafness, animate dead, bestow curse, etc. The War domain also gives you real potency as a front-line combatant. Your AC will already be formidable, plus you can use domain abilities to gain bonus attacks and a +10 modifier to your attack roll using Channel Divinity.
2) If you wanted less spell power and more attacks, consider the Eldritch Knight subclass for the Fighter. You're (mostly) restricted to abjurations and evocations, but that includes some nice fire spells like burning hands and scorching ray. If you want to stay strictly with the "death" theme, then take the chill touch and poison spray cantrips, and note that you can select non-abj/evo spells at higher levels (allowing you to take things like ray of sickness or contagion).
3) You could also look at the warlock, but I'd suggest this isn't as appropriate as the two options above. Warlocks are a little trickier to play, and they're not nearly as durable on the front line as a heavily-armored war cleric or eldritch knight. But they have some nice theme: summon a magical blade to your hand, throw bolts of eldritch energy, and they have a heap of death-related spells.
