So after reading a great deal here & there I finally managed to summarise what I feel maybe right for an input that is grainy. To be comprehensive my input has dancing pixels & decreasing crf value increases file size such that its not optimum for me, I have varied values b/w 21-23 but the result still is grainy...I thus desired to use a some de-graining techniques two of which were built in x264cli. Now the gurus here might shed light of whether the generalised solution are appropriate & what other solution they recommend me to fiddle with
Below are quotes from across internet
  1. If you like a clean picture and don't mind a little bluriness try 1:2. --deblock 1:2
  2. Temporal is particularly good for videos with what I like to call “dancing dots” or “dancing pixels”. For example, when a surface in the video like a wall (which should look pretty static) is grainy and that grain continually moves/dances around during playback (despite looking ok when paused). The temporal denoiser does a pretty good job of noticing this and denoising these areas while leaving the other stuff that looks fine alone. --vf hqdn3d:2,1,7,7

Further Notes:
The input file has a constant bitrate histogram (bitrateviewer) ~5100kbps
My output with --crf 23 --tune film has a great spectrum of bitrate variation such that its avg value of 2200kbps means nothing, why because the scenes which are grainy lie in the range of 3800-4300kbps while the rest mere ~1800kbps(perfect quality), thus grainy scenes are deliberately increasing file size with no quality gain
Input file is a drama with some fast moving scenes like waving hands, some dance & a little bit of slapping, but not detail hungry scenes like scenery etc. though I would like character face detail & skin tone NOT to be pixelated
Code:
Format: Windows Media 
VideoFormat: VC-1
CodecID: WMV3
Resolution: 1280x720
DAR: 16:9 or 1.778
PAR: 1.000
VideoBitrateMode: VBR
ScanType: Progressive
AudioCodec: WMA
AudioBitrateMode: CBR