How Will The Dent On The Rim Of The Coin Impact Its Gradation

Depending on the number and severity of the dents, they always have a downwards effect on the grading.

Can see evidence of light cleaning in the field on the obverse, almost hidden due to many years of subsequent patination. Careful examination under high magnification should confirm.
This coin EF (British grading), downgrades to
gVF, due to the rim dents, IMHO.

Somewhat of a pity, because overall it is a rather attractive looking coin, where the nice eye appeal should help the value.

Coin has only been lightly cleaned.
If you compare the obverse field in front and below Vic's chin with the protected fields on the reverse, light cleaning becomes apparent. As I noted you will need to look in these areas with a 10x loupe to confirm.

10x loupe is the tool that TPGraders use for close examination, for standard grading technique, when coins are slabbed.

Light cleaning like this can be obscured by a good patina. There is not much underlying lustre under the patina, although some remains.

I also note a faint circumferential die crack on the top of 'GINA'.

I have an 1887 Half Crown (most common date for this type), in about the same condition