You can instantly charge the sentinel clip with any character!
Much easier way to do Insta-Charge with All Legends
It really is that simple; throw a Holospray (even with Sentinel in your hands), then hit the charge Sentinel clip button.
Many thanks go to Kafeinator to find out all you need is a Holospray to instantly charge a Sentinel clip. Remember to have a Shield Battery on your person to be able to charge clips. All Legends have Holosprays, so make one equipped and you can charge instantly every time you throw it.
Limited and More Complicated Version of Glitch
There has been a lot of clips and articles going around today about Revenant and other Legends with one handed tacticals that can charge the Sentinel instantly.
However, the steps for this to work can be complicated enough to not get it done right every time; You have to holster your Sentinel, then use your one handed tactical, pull Sentinel back out, and finally hit the charge clip button.
Have some fun with those charged shots!
Stay frosty Legends