Hahava has approximately a 2% drop rate on Ganesha's Mala. This is not particularly rare considering:

The expected value of a geometric distributon with p=0.02 is 50 (the average number of Hahavas before a player receives a Mala is 50). The standard deviation is 49.5 so 68% of players will receive the Mala in 1-100 Hahavas. 95% of players will receive a Mala within 150 Hahavas and >99% of players will receive a Mala within 200 Hahavas.

It sounds sort of awful, but SE doesn't consider a single Hahava to be an event - they consider one "event" to be 6 Hahavas. In other words, 68% of players will have a mala within 17 runs - 95% in 25 runs, 99% in 33 runs.

We can calculate the actual value of how likely you are to get it in a set of six but we can also extract it from the above information! Based on this progression your actual chance to get a Mala in a single "event" has a standard deviation of 8. Since we know it follows a geometric distribution, we can determine:

8 = sqrt( (1-p)/p^2) --> 64p^2 +p -1 = 0
---> p ~= 0.117 (this is slightly on the high end since we did a lot of rounding)

So you have a ~11.5% chance to get a Mala every time you do a set of Hahavas, which is pretty reasonable in my opinion.

As for pulse weapons, they are supposed to be extraordinarily rare and most of them are so incredibly situational (if they're useful at all) that you shouldn't be pulling your hair out over them anyway.