Try to use ROC (Rate Of Change).

https://www.investopedia.com/terms/p/pricerateofchange.asp#:~:text=The Price Rate of Change (ROC) is a momentum-,certain number of periods ago.

...
import qnt.ta as qnta
...
def single_pass_strategy(data, wma_period=20, roc_period=10):
   wma = qnta.lwma(data.sel(field='close'), wma_period)
   sroc = qnta.roc(wma, roc_period) # it measures the angle (tg)
   weights = xr.where(sroc > 0, 1, 0)
   return weights
...

Regards.