This build… is very bad. I don’t even know, where to start.
First of all, welcome to the forums mate 
Ok, about the build. Mixed damage on a build is usually a bad idea. I guess you were trying to get something like a cold/vitility hybrid - that’s not going to work at all. I suggest you focus on cold for example, because that’s on of the easiest damage types to understand. Reaper isn’t the best option for cold builds, but it’s ok.
Ok, now we have a damage type to work with. One of the most important things for every build is to get resistance reduction. There are 3 types of RR (resistance reduction): % reduced, -%, and so called “flat” rr (smth like 30 reduced, for example). Just remember % reduced and flat - don’t stack with themselves, only the highest is applied. -% stacks with each other, when it comes from different sources. When you design a build, you must get all the available sources of rr that you can (especially the -% that stacks with each other). This will increase your overall damage and allow you to deal with some resistant mobs and stuff.
Now, that we know about the rr and how it works (well, kinda), let’s talk about skills. Most builds have the primary damage skill that it focuses on. In case of the cold Reaper, this skill can be Bone Harvest (with the Harvester of Death transmuter of course). You want to maximize this skill, invest as many points as you possibly can in the skill itself and in most cases - in the whole skill line.
Let’s look closer to Bone Harvest. This skill has WD (weapon damage). this means that it benifits from falt damage sources, like Nightblade’s Lethal Assault for example. What you can do, is you can cast ABB (Amarasta’s Blade Burst) first and then cast your Bone Harvest, to get a lot of damage. You also want to have some falt damage on your gear as well.
Ok about the gear and other skills… I’ve theorycrafted a cold Reaper as an example for you, so you can see how this build is supposed to look like. Not the best Reaper out there, but it’s ok for the MC. Feel free to ask any questions 
https://www.grimtools.com/calc/qNYYpdXN