It's ability states that this Pokémon's moves have 0.1x more power, but then says maximum is 1.5x. If we express 150% as 1.5x (which is consistent with how stat changes are represented in battle on Showdown), then we should express a 10% boost as 1.1x. since the Pokémon's attack is 110% now.
0.1x may confuse a user into thinking that the Pokémon actually gets weaker with every fainted ally.