Don't do it. It's just frustrating. Tried Movie Studio and it was bad (slow for the simplest things). The problem is that (mobile) ARM is not very well suited for some tasks. Video editing being one.

If it must be light and a tablet. Get a surface pro. I edited 4K video on my Surface Pro 2 with Premiere the other day. I obviously had to use proxies, but it worked very well. The Pro 3 should be even better.

I would try WeVideo.

WeVideo charges a monthly fee for anything beyond 480p. No thank you.

I looked for such an app just a couple weeks ago. The only app that seemed to have reviews that were both positive and credible cost $6 per month. The others either didn't work well or required that content be uploaded and rendered on their servers.

I've used iMovie on my iPhone to edit 1080p HD video and it was very, very smooth. Edits, transitions, and effects are realtime and rendering is pretty quick. If you go the tablet route it's worth checking out the iPad, as AVID makes an editing app for it.

i am NOT trolling...

after 40+ years in tv and video i cannot grasp the idea of editing video, especially hd, on a (regular) tablet, let alone a mobile phone. (i often edit on an i7 laptop, but even that is no substitute for a proper nle seup).

what circumstances would induce one to want to edit on such ill suited equipment?

"what circumstances would induce one to want to edit on such ill suited equipment?"

A long flight.

Basic editing actually works fine on an iPad. Where it loses it for me is in things like color correction, stabilizing, video noise reduction, audio noise reduction, etc. What I would love to see is a simple Sony Movie Studio type of app where you could do a basic edit, then load it into regular PC Vegas Pro for further editing and tweaking. That or something that would let you edit with the proxies that the current SCS helper app uses instead of just trimming and adding markers.

Problem with Androids is even with a microSD card most are well under 100 GB. Not enough to do anything serious, and external OTG is pretty much a thing of the past with Kitkat.

Get a Surface Pro, 2 or 3 depending on the video you are editing. Runs Sony Vegas Pro like a dream - my Pro 2 has Vegas, Adobe CC (Premiere, Lightroom and PS) running. It works great. Will get a Pro 3 with an i7 some time soon.

Thanks everyone for your suggestions. My interest is simply occasional editing of material shot with the device (in this case a Note 3 ... ) on those occasions when I have lots time eg on a ferry or train or in 'the bush' .
The only android editor which impressed me is Kinemaster Pro (timeline based and seems remarkably responsive on the note 3) which until recently was purchasable by a one time fee of around USD3 (otherwise it remains watermarked). The cost to remove the watermark is now USD5 per month or USD45 / year which for occasional use is too expensive in my view.
Graham