how to counter dragunity legionnaire and aklys combo?

Just get a card with negation effects such as:

Divine Wrath:

Discard 1 card to negate the activation of and effect monsters effect and destroy it. (Does not matter if it already dies effect is negated either way.)

Skill Drain:

Pay 1000 Life points. All effects of effect monsters are negated. (Sorry yours included)

Solemn Judgement (maybe):

Pay half your life points, negate activation of spell or trap or summon of a monster.

This was all I can think of... Hope this helps, and good luck.

Aklys would still activate because it was sent to the Graveyard while equipped to a monster.

The best way to defend against it is to stop it from happening. You can either negate the Summon of Legionnaire, negate its effect to equip itself, or activate any card that will stop Legionnaire from being face-up on the field before it activates its destruction effect.

Negate the Summon:

Solemn Judgment

Solemn Warning

Horn of Heaven (I don't recommend this)

Negate the effect:

Effect Veiler

Divine Wrath (I don't recommend this)

(I'd also like to note that Chaining D.D. Crow or a similar card to Legionnaire's effect and removing the target will cause Legionnaire to resolve without effect)

Remove Legionnaire from the field or flip it face-down:

Book of Moon

Trap Hole

Compulsory Evacuation Device (I don't recommend this at all)