5e seeking sword

[Sixo2]

I've been playing alot of the old school d&d games on my tablet lately and fell in love with the cleric of helm's Seeking Sword.

" This spell creates a sword in the clerics hand. The sword is considered a plus 4 weapon for the purposes of determining what it can hit and it deals 2d4 damage to targets it hits. The weapon sets the number of attacks of the cleric to 3. It lasts for one round per level of the caster. When equipped the cleric can no longer cast spells."

My question is, how would you guys and gals convert this ability to 5e? My thought was replacing one of the war clerics abilities.

 

[aco175]

I do not have a problem with allowing it to hit creatures you need magic weapon to hit, or the 2d4 damage. I would be careful with allowing clerics to get more than one attack per round. You could make it a concentration spell for 1 minute and allow another attack with the characters bonus action. He could still cast a spell but give up his attack or his bonus attack. Maybe make it so the only spells he can cast is bonus spells.