EDIT: You don't have Disguise as a class skill.
Er, the capping by class level part was the problem. If you're lv20 and have 1 level in this class, then making a weapon +1 instead of drawing your +5 sword hardly even counts as an ability.As for the scaling thing... Maybe start it out low, and scale with IL, or something? Cap it at half class level, of course.
The ability as written would let you switch Legacy Weapons but not use one unless you had the feats already. And a UMD bonus would mean that you could also attack with wands; it's kind of weird that a guy with the theme of "can use anything as a weapon" can't use a weapon that a random thief can.Maybe the UMD thing will be changed to "you are able to weild any weapon with a special requirement, such as being only usable by elves, or being only usable by clerics, as though you met that requirement.". Does that read better?
As for the meh part...
It says "specific weapon". Weapons of Legacy grant you feats for each specific one.
Yes, and the main reason to take 6 levels of horizon walker is to become immune to fatigue. Doesn't make it a good reason, when you can get both at lv1.Also, isn't the main reason to dip Master of Masks access to all weapons? Because you get proficiency with ALL weapons as well.