There is a show case video in mod videos. Please check it first.
Can be used with my True Warfarer Mod. 
Difference with other skill swapper mod 
It is more like an in-game 8 skill slots, instead of rotating the existing 4 skill slot. It wont break the skill context in game.
It seems there are some bugs cannot be solved in the way I use before.
So I uploaded a new version(1.1.0), which use skill set rotation just like the other mods. 
Like the mod name, it is an alternative one. Just in case it can fulfil someone needs.
Installation
Download the mod file, Drag the zip to Fluffy or Unzip to the game folder.
Make sure 
1. AnAlternativeSkillSwapper.lua located in gamefolder\reframework\autorun
How to use
It's a little tricky to config this, so please read following carefully.
For keyboard users:
1. Set a secondary key to Switch Weapon Skill in game settings
2. Press insert to open ReFramework UI
3. Go for Script Generated UI -> An Alternative Skill Swapper
4. Set the modifier key with your secondary key set in step1
5. Set all slot keys. Make sure it is SAME as you set in game. It's just let the mod know your in-game key settings.
6. Set your alternative skill slot by vocation.
7. Try it out!
For controller users:
A little complicated for controller users.
1. Refer this video to learn how to set up your steam input.
2. Set a secondary button for your Switch Weapon Skill button. For example, If you wanna use L2 /LT as your secondary Switch key, set L2/LT as LCTRL.
3. In game settings, set the LT with a Run or Camera or anything won't block skill casting.
4. Following the step 4 - 7 as keyboard users do.
There are some samples in mod images.
NOTES
The alternative skill you set MUST behind some of you in-game active slot.