{Somename Thatguy}, Imperial Commander
Legendary Creature - Human Soldier
2WW
As ~ comes into play, choose a colour.
Tap, Tap an untapped nontoken creature you control: Destroy target creature of the chosen colour.
2/2
'As' seems more appropriate, and less likely to cause any rules confusion

Yes I know the rules say otherwise but if two people don't know the rules properly.. especially in a casual game.. it's safer that way

So it looks like another attempt at remaking Hand of Justice

(For reference: HoJ from Fallen Empires, 5W for 2/6 Avatar, T, Tap three untapped white creatures you control: Destroy target creature.) Or, as it's been suggested, compare it to Northern Paladin (2WW for 3/3 Paladin, WW, T: Destroy target black permanent.). If you're comparing it to that, you lose +1/+1 for the choice of colour, and trade WW for tapping a nontoken and targetting only a creature - and this is Legendary now. As the Northern Paladin made it into 7th, I presume they consider it pretty balanced, since it was lost after 4th.
I suggest that if this is to be nonlegendary and on par with the Paladins, that it come up as this:
WW2 cost for 3/3 instead of for 2/2
Activation ability should cost tapping it and perhaps tapping two other creatures, or sacrificing a creature. In other words, either one of:
Tap, Tap two untapped nontoken creatures you control: Destroy target creature of the chosen colour.
Tap, Sacrifice an untapped nontoken creature you control: Destroy target creature of the chosen colour.
Making this card legendary, I'd leave the size at 3/3 and drop the activation to where it was (tapping it and another creature).