Does this mean my proficiency gets boosted quicker?

I think it means in stead of 10 prof per monster max it is now 15. So not faster, but more if your fight goes on long enough

It allows for 50% more prof per wave. So instead of a max possible of 10 you can get 15 points instead

Thank you for clarification

As stated above. Here is a bit more clarification for any other readers that don't know.

You have a chance to gain 1 prof point per single action (zero[0] damage = zero[0] chance of gaining a prof point) during an Encounter (Wave) of monsters. (When you press Engage or T). The maximum is 10 per encounter (wave) you can gain. [Some monsters like Gigabee / Slugslider "Call for Help" and are regarded as monsters of the same wave, thus you can NOT gain anymore prof points once you reached the maximum of 10]

+50% To Proficiency Cap Per Fight = Maximum of 15 per wave.

Now, from previous testing by others, here is a rough estimate of the % chance rate of items:

Weapons have a 20% chance to gain prof point(s) per single action
Cast Charms have a 50% chance to gain prof point(s) per single action
Healing Charms have a 75% chance to gain prof point(s) per single action

When using Abilities like Multi Cast / Strike & Heal in one action, you have a chance to gain more than 1 proficiency point.

Hope this helps.

Oh, if your Hit Check = 0, you won't gain any prof point(s)

Now you have me wondering, is that 50% prof per mastery or total?

Total sorry I forgot to mention it earlier.

You can not attack and get maximum prof for your weapon (10 or 15 in this case) and try to get another for Healing or casting, once you hit max per wave, that is final, you need to clear the wave for the Prof counter to reset.

Ive been using this to heal myself on the spider waves after I kill the real one. Just spam my heal to get some prof

I do this as well, at least you get the prof gains for healing, I will also spam heal when my level gauge is @ 98% (e.g. level 15.98) before level up.