Complex sentence: David Gavrushevich Avanesyan (born 15 August 1988) is a Russian professional boxer of Armenian descent, who has held the WBA (Regular) welterweight title since February 2017; previously he held the WBA interim welterweight title from 2015 until being promoted.
Split into simpler sentences: David Gavrushevich Avanesyan (born 15 August 1988) is a Russian professional boxer. He has held the WBA (Regular) welterweight title since February 2017, having held the WBA interim welterweight title from 2015 until being promoted.