Take out affects the caster and lower accuracy and its good. Maybe worth adding a radius of effect.

Looks good. Would still recommend a radius of effect on the explosion. If you don't add that then consider this accepted.

Take an example from this grenade:

M67 Fragmentation grenade - Your classic grenade, used by numerous military forces around the world. It has a 6 second timer. And no, it does not deal holy damage, even though we did have a man called Monthy test it on rodents. Cost 50 dollars.
15 explosive damage if within 1.5 metre, 10 explosive damage between 1.5 metre to 3 metre, and 5 explosive damage between 3 metre and 6 metre. AP 3.

Depends on how much range is on the explosion.

What would the dimensions of a medium-sized room be to you?

So thats a radius of two and a half metres. sounds fine by me.

You should edit in the range of the explosion itself