You CAN make a build purely dedicated to sleight of hand only if you REALLY want to. However, Sleight does not scale and the damage will drop off, unlike Saryn / [Octavia]. This combo set up allows you to have 30 seconds of mirrors and eclipse while having 76m range with sleight which in my opinion is good enough and personally I can't sit around just spamming sleight unless I'm doing fodder because I lose brain cells. If you have [Primed Sure Footed] use it. If you don't use weapons with a knockback an alternative would be [Rolling Guard] for survivability. [Mirage] = squishy.

The umbra forma is there to help variety for swapping things out depending on mission and if I'm in steel path. (For other Config)

Bramma builds I run with Mirage
https://overframe.gg/build/190582/kuva-bramma/kuva-bramma-config-a/
https://overframe.gg/build/190838/kuva-bramma/death-awaits-thee-riven/ (Riven Variant)

Config A: https://overframe.gg/build/190573/
Config B: https://overframe.gg/build/190577/