To get the benefit of a Ryeser Critical Effect you must:
-Be faster than your target
-Be able to hit/crit your target
-The target must not RESIST! lightning.
Ryeser currently scales off of SKI/LUC at a 45/45 ratio (pretty good, if you ask me). Which means that for your HIT/CRIT and damage stats, you get to scale off of SKI and LUC alone. This leaves you very open ended on what you can and cannot do with the weapon, because so long as you have a decent amount in those stats (50-60ish) you'll be fine. To this end, you are set for your hit/crit, because they're light enough to benefit from an extended grip + lightweight for fitting form (more hit and crit for caveat #2.).
Now how does one get rid of Lightning Resist? The most obvious form of Lightning Resist comes in the form of the Beldam Aegis, to which most tanks generally use if not fangfaced, etc. Cripple arm will get rid of this. However, if you do not particularly want that. You can instead use NULL SHELL (with your gun. Because Magic Gunner) and laugh as you ignore the lightning resist with impunity. (Caveat #3 solved)
So the only issue is that you must be faster. Which.. is relatively simple due to only dodgers really taking it (who would be the hard-to-hit people anyways). If you want to assure your CEL based victory, tossing some 20-30 points into it, you'll satisfy it in most every case, and the other cases you can build up guile (or other things) to promptly make your opponent cry as you get behind them with your movement and crit their rear.
What does the critical effect of the Ryeser actually do though?
Well it removes 1 Momentum from the target so long as you fulfill every caveat above. Hit them, crit them, act before them, and let them not resist it. This effect can stack multiple times, and on a 2 round gun (3 with an extended grip) and akiimbo.. you get about 4-5 shots every time you shoot. If you dual wield ryesers, or are simply a Duelist (because why wouldn't you be with a build that focuses on hit/crit).. this means that you get about 12-15 shots.. which can reduce your opponents momentum down to 0.
What happens when their momentum reaches zero? They lose their turn, they automatically "END TURN" and do not get to act that round. They do not get 'immunity' to it (as one does with stun) to prevent it from happening next round. Nor do they get any real indication or way to fight back against it besides "have high enough crit evade (hahahahhahahaha having enough crit evade to fight against stats... 155 crit evade didn't do anything and he had 38 crit before he buffed)' so. There's no real way to win, and you only lose in this situation.
How to fix;
Make it only remove up to 2 per round??? Idk.